Original subtitles

- I'm Craig Melvin and this is "Dateline: Secrets Uncovered."

- I can't even believe she would meet someone

at a park at 3 A.M.

I think she knew the second she got in his car

that something was wrong.

- A college student disappears.

- A secret life uncovered.

- She was on a dating site looking for sugar daddies.

- Going into it blindly

is not something I would recommend.

- Chilling details revealed.

- Is this guy dodging us?

- He kind of selected her as his victim.

- Correct.

- Towards the bottom of the dig site,

there was a damaged iPhone.

- Looked like maybe clothing.

It was just a sinking feeling, really.

- I just replay this one night I had with her

and I just wanna grab her and say,

"Don't do it. Don't go."

**

- Hello, and welcome to "Dateline: Secrets Uncovered."

For parents, it is natural and scary

to watch their children become independent.

College student MacKenzie Lueck

was striking her own path to adulthood

and she knew what she wanted.

But MacKenzie did not know

what she was getting herself into

until she disappeared into a secret underworld.

The race was on to save her.

Here's Keith Morrison with "The Waiting Car."

**

- Our minds have a curious way of deceiving us.

We sense something off.

Something wrong. Even terrible.

And yet, something in the brain wants to believe

the worst didn't happen.

Kennedy Stoner knows that feeling well.

- I was kind of pushing away from my gut instinct.

I'm not really sure why.

I never imagined this ever happening

to one of my friends.

- I wouldn't think you'd want to imagine it, right?

- No, or anyone that I know.

Or-- So, my mind didn't go there.

- So, she told herself it would be fine

as she reached out from her home

here in Salt Lake City, Utah.

Messages to her friend MacKenzie Lueck.

- I saw that she wasn't opening my Snapchats.

And I had texted her and I didn't get a text back.

And this is stupid, but I was kind of wondering

if she was mad at me for something.

- The mind wants a simple explanation.

After all, she knew her best friend was grieving.

MacKenzie's grandmother had recently passed away

in California.

- I know she was heartbroken over that

and so was the rest of her family

because they're all very close.

- And she went to the funeral.

- She did. She left Utah. She went to the funeral.

So, I was thinking maybe she just, like,

took a few days off social media or something.

- MacKenzie's parents, though, hadn't heard from her either.

After 3 days of escalating fear,

MacKenzie's dad made that most dreadful phone call

to the Salt Lake City Police Department.

- The story MacKenzie's dad told was this.

On the night of Sunday, June 16, 2019,

MacKenzie had boarded a flight from Los Angeles back to Utah,

arriving in Salt Lake City around 1:35 A.M., Monday.

At 2:01 A.M., she texted her mom

to say she landed safely.

After that, three days of silence.

Two patrol officers went straight away

to MacKenzie's townhouse.

Her car was in the driveway. That was a good sign.

[knocking] Repeated knocks at the door,

however, went unanswered.

Peering through a window, the officers saw nothing.

Not a soul around.

They called MacKenzie's dad to report the news.

And next, the officers phoned MacKenzie's friends,

and boss, and professors.

None of them had seen her.

All reasons why,

by the end of this unsettling day,

MacKenzie's case was referred to a place

that sounded very serious indeed.

The Salt Lake City Police Department's

homicide squad.

- We get a lot of missing persons cases

in Salt Lake City.

- Lieutenant Todd Mitchell was the unit's chief detective.

- So, I try my best to sift through those

and find the-the ones that kind of raise the hair

on the back of your neck, for lack of a better term.

And this raised the hair on the back of my neck.

So, that's why we decided,

yeah, we need to take action now

and-and at least start a-an initial investigation into it.

- Truth be told, most reports are easily resolved.

The missing person may have simply lost their phone

or just decided to take a break

from some family drama.

But that didn't appear to be the case with MacKenzie.

The relationship she had with her mom and dad

would be the envy of most parents.

- They were always contacting each other.

They'd send little silly texts back and forth

on a daily basis.

- Detective Nate Wiley and Tiffany Sayes

led the missing persons investigation,

even though their specialty was murder.

- I mean, in a usual homicide investigation, we start--

there's a dead body. We're starting with something.

We have a-a victim and we're moving backwards.

In this case, we started with nothing.

- First action Sayes and Wiley took

was to pull the Salt Lake City Airport

surveillance camera footage

from the night of MacKenzie's disappearance.

And sure enough, there she was.

- So, it was nothin' out of the ordinary.

We're able to see her come off the-the terminal

and we followed her all the way down to the baggage claim

to where she picked up her luggage.

- Seemed perfectly normal, fine, causal?

- Yes. Nothing out of the ordinary

that we could see at all.

- The last clip shows MacKenzie,

like so many other passengers,

casually getting into a car outside baggage claim.

But the identity of the driver?

A mystery.

News of the police investigation

quickly spread among MacKenzie's friends.

- The second that I heard about that,

my stomach dropped.

- So, Kennedy launched her own investigation.

- I went on Facebook.

I dropped pictures of us together

and I said, "She's missing."

Like, "If you know anything, reach out to me.

"Reach out to police."

- I thought she was still in California

until I saw Kennedy's message on Facebook.

- Ashley Fine, another of MacKenzie's college friends,

put up her own Facebook post.

- And I tagged her in it.

And because I tagged her Facebook,

some of her other family members

reached out to me immediately.

- What family members?

- Um, some of her distant cousins.

- Okay. - One who lives here in Utah.

And we started talking and messaging.

And I said, "You know, I have a feeling

"that she took a Lyft share.

"I feel really strong that she did that."

- So, you're worried that something may have happened--

- Definitely. Definitely. - In that car?

On their own, Ashley and this cousin called Lyft

and Uber to see if either one of them

had picked up MacKenzie at the airport.

- And that's really when this began,

because somehow, they let it slip. Lyft did.

That she got in a Lyft that night.

- What did you do at that point?

- We contacted law enforcement about the Lyft.

- A big break for Sayes and Wiley

because it gave them probable cause

to serve Lyft with a search warrant.

- And find out where her destination was,

where she was dropped off, what time she was picked up.

- Where did she go?

- So, we were able to get the destination from the airport

all the way up to a North Salt Lake address

and she was dropped off at Hatch Park.

Up in North Salt Lake, just before 3 A.M.

- A park? At 3 A.M.?

Why would MacKenzie come here?

And just as important,

why would a driver leave a young woman alone,

burdened with luggage,

at a park in the middle of the night?

Who would do such a thing?

It was Detective Sayes' job to track down the driver.

Who, she discovered, was not so easy to find.

- We were like, is this guy dodging us?

- MacKenzie's friends have a terrifying theory

about why she's missing.

- I assumed that the Lyft driver abducted her.

- We wanted to know if he was in fact

going to be a suspect or not.

- And here's one reason why.

- Her last text message that we recovered was at 2:58,

prior to her arriving at the Hatch Park location.

And that was the last activity ever we had on her phone.

**

- Before MacKenzie Lueck disappeared in June 2019,

a disturbing story had gone national.

Several stories, actually,

about women being assaulted while using Lyft or Uber.

- At least 14 women have now filed a lawsuit

against the rideshare giant.

- And perhaps no surprise,

MacKenzie's friend Ashley Fine

imagined something like that, or worse.

- I assumed that the Lyft driver abducted her

or maybe they were in a car accident

and their car had driven off the road.

- The detectives thought that was a possibility, too.

So, they wanted very much to find

that elusive Lyft driver

who gave MacKenzie a ride the night she vanished.

- We wanted to know if he was in fact

going to be a suspect or not.

- He was, though, nowhere to be found.

Just as odd?

MacKenzie's phone, the detectives learned,

was turned off

just as her Lyft ride came to an end.

- Her last text message that we recovered was at 2:58,

prior to her arriving at the Hatch Park location.

- Mmm-hmm?

- And that was the last activity ever

we had on her phone.

- On the morning of Saturday, June 22,

Six days after MacKenzie went missing,

Detective Tiffany Sayes finally tracked down

MacKenzie's Lyft driver.

- He says there wasn't a lot of conversation

going on in the car.

He did recall her being on her phone,

um, but he didn't know who she was talking to.

- Was he fully cooperative? Did he seem--

- Oh, yes. Definitely. - Like he wanted to help you?

- He did. He didn't-- He didn't seem...

...like he had anything to do with this at all.

- Because he had an alibi.

A very good one, actually.

As soon as he dropped MacKenzie off,

surveillance footage at a nearby intersection

captured him leaving to pick up another fare.

The date, time, and location

all confirmed by the tracking software on his Lyft app.

- And he continued that through the night. And so--

- So, you could eliminate him pretty easily,

based on the fact that he was elsewhere.

- Very quickly, yes. - She was smiling.

Um, she was in-- uh, in good spirits.

- MacKenzie's Lyft driver, Heath Canada,

told police and later, us,

he remembered the weird drop-off location.

Even MacKenzie commented on that, he said.

- Saying how it was odd to be dropped off

in the middle of the night at a park.

- Canada, though, said he wasn't too worried

because someone with a car

was there waiting for MacKenzie.

- I unloaded, um, her luggage.

Said goodbye and drove away.

- So, who was that someone in the waiting car?

The detectives were hoping they could identify him

or her through MacKenzie's phone records.

And she had been texting a number with a 206 area code

right up to the point her phone went dead.

- So, we were able to actually take that number

and run it through our little databases

and it came back as absolutely nothing.

Didn't come back to anybody.

- Had to be some type of burner phone, they thought.

So, whoever that was did not want anyone to know,

uh, anyone in any official capacity,

to know who it was.

- Yeah, it was pretty obvious at that point.

- But according to the Lyft driver,

whoever met MacKenzie at the park

made no effort to conceal their identity from her.

To the contrary.

- They seemed to know each other, um, really well,

'cause I-I think all I heard was,

"How are you doing? How was your trip?"

Just kind of basic, uh, greetings.

The situation seemed real-- very safe.

Uh, she, uh, obviously knew the person

that she was, um, getting in-- um, into the car with.

- That MacKenzie had caught a ride with someone she knew

was both good and bad news.

The good news, of course, was it meant

maybe MacKenzie just went off with a friend somewhere.

The bad news?

Because there was now no proof of a crime,

the detectives had lost their power

to get any additional search warrants.

- We had lost our-- what we call "probable cause"

that a crime had been committed.

And so-- - Just like that?

- Just-Just like that. - Because of this supposedly--

just because of what the Lyft driver said,

suddenly, you can't be getting warrants for things.

- Correct.

And so, that was a hard part and it really slowed down

the investigation at that point,

because we didn't have a crime to attach to it.

It was still now just a missing persons investigation.

- Without a warrant, the detectives were blocked

from getting detailed phone records,

which, theoretically,

would have shown who MacKenzie was texting.

So, who was this friend MacKenzie met at the park?

And where did they go?

- MacKenzie's phone is off,

but investigators have other ways

to follow her digital footprints.

One place MacKenzie wasn't missing

was on social media.

- Different people stating,

"Hey, I'm looking at her site right now.

"It's showing that she's actively online."

- Her bank account was active, too.

- So, we were hopeful that there would be

further transactions on there, so that we could find her.

**

- So many questions.

Why did MacKenzie go to a park eight miles from home,

at 3 A.M. no less?

Who did she meet?

It made no sense, thought her friend Ashley Fine.

- I can't even believe she would meet someone

at a park at 3 A.M. It's just so unlike her.

- It is? - So unlike her.

- Because MacKenzie,

like most of her sorority sisters,

had talked a lot about safety.

- I mean, I've been out with her a lot of times.

- Yeah?

- And she's always been extremely safe.

She's texted me after going out at night

and said, "Hey, did you make it home?

"Are you okay?"

- You would exchange things just to keep each other safe?

- Mmm-hmm. Yes.

- Ashley had met MacKenzie almost four years earlier.

- She was a little bit shier

than people would think she would be.

- Mmm.

- But once you got to know her,

she had a big personality. She could make anyone laugh.

- Kennedy Stoner also met MacKenzie in college.

- Her family doesn't live here.

- Mmm-hmm.

- So, she was all on her own here.

So, she had a job. She was going to school.

She was, like, checking off everything

that a responsible adult

would have on their checklist, I guess.

- MacKenzie grew up near Los Angeles.

El Segundo, California.

And she was raised in the Church of Latter-Day Saints,

but when she came to the University of Utah

to study Kinesiology, according to Ashley,

MacKenzie didn't exactly remain devout.

- I know she was registered here at a ward in Salt Lake City,

but I heard that she was never active

and that makes sense to me,

because I think she wanted to find her own path.

- You saw her changing. - Mmm-hmm.

- In recent times, didn't you? - Mm-hmm.

- In what ways?

- I think she was trying to almost gain confidence

and security in herself.

She'd always write herself, like, notes

saying how she wanted to feel more confident

because I think she realized she was really shy

and she wanted to be more outgoing and meet people.

And she wanted to explore dating

and-and, um, and it might not be how everyone else

thinks that dating should be.

- What Ashley is getting at

is that MacKenzie was active on dating sites.

So much so that by Saturday June 22,

the sixth day after MacKenzie's disappearance,

detectives had received several phone calls

from some of the men MacKenzie met online.

Mainly to say they had nothing to do with her disappearance.

- I mean, nowadays, that's how people meet people.

So, while it was of significance

because it gave us, you know, one more thing to look at,

it wasn't this, you know, big, huge red flag either.

- So, was MacKenzie off on a lark

with a guy she met online?

A hookup she wanted to keep secret

from her devoutly-religious parents?

Well, that certainly seemed far more likely

than some sort of kidnapping scenario.

- She could've gone camping or have gone with a friend

where they would lose cell service

and it wouldn't be out of the ordinary.

- But once I did some checking around,

that camping idea seemed a lot less likely.

Why? Standard procedure.

They looked up airline flight records

and discovered MacKenzie had been booked on a flight

out of town, to Las Vegas. So, maybe she was there.

And meanwhile, the detectives began to see activity

on her bank account. And something else.

- Different people stating,

"Hey, I'm looking at her site right now,

"it's showing that she's actively online."

- So, maybe she was just fine. Ignoring the fuss.

Or zoned out and entirely unaware of it.

- And so, we were hopeful. - Sure.

- 'Cause, when people go missing,

even if it's on their own accord,

they're still going to be making transactions

or paying for stuff.

And so, we were hopeful

that there would be further transactions on there,

so that we could find her.

- Not far from the police station,

Kennedy and Ashley hosted a rally

to make sure everyone in Salt Lake City knew

to be looking for MacKenzie.

- Hey, guys. This girl's missing

and we're looking for her. She could be in danger.

We think she's in danger.

- But, was she?

On Sunday, June 23,

detectives learned MacKenzie had a flight booked

for that very day, traveling from Las Vegas

to Los Angeles to attend a friend's wedding.

- And she wouldn't miss that.

So, we contacted, uh, LAPD

and they had officers waiting for that flight to land.

- They waited by the jetway

for all the passengers to de-plane.

MacKenzie was not among them.

Then, they learned this.

It wasn't MacKenzie

who'd been logging into her social media accounts.

That had been her friends.

- They'd obtained her email and password.

And they weren't doing it

to try to ruin things or anything.

They were tryin' to go on there

to monitor the sites as well,

to see if any information could come up.

- And the activity on MacKenzie's bank account?

- It was the Lyft transaction on the 17th,

and then an automatic payroll deposit from her work.

- And then, the detectives got a tip from this guy.

Who, just maybe,

could bring all those blurry details into sharp focus.

- I got on the computer and within an hour,

two hours, I had found her profile.

- I didn't know anything about her being on that site.

- The world of sugar babies.

- I think we're living in a culture

where it's much more accepted and embraced

for women to be upfront

about what they need and want.

- Did MacKenzie know what she was getting into?

- A lot of people who go into it

are, like, seriously so blind

to like, the whole reality of what it is.

**

- Welcome back to "Dateline: Secrets Uncovered."

I'm Craig Melvin.

College student MacKenzie Lueck vanished

after secretly meeting someone at a park at 3 A.M.

Why rendezvous there at that odd hour?

Now, a tipster was about to share troubling details

of his encounter with MacKenzie

shortly before she went missing.

Back to Keith Morrison with "The Waiting Car."

- It was a few weeks before MacKenzie Lueck vanished.

A chance meeting at a bar with this man, Rob Joseph.

- She just seemed like a very bright,

uh, bubbly girl. Um, friendly.

- They talked for more than an hour, said Rob.

Or she did while he listened.

Rob is an ex- Salt Lake City cop.

Private eye now.

Which, of course, he told her.

- If you mention you're an ex-cop and you're a PI,

everybody all of a sudden wants to tell you

their dark secrets, you know?

Or-Or risky behaviors.

- Is that what happen-- is that how people react, truly?

- Oh, yeah.

You'd be surprised that people just wanna tell you things

that you don't wanna hear.

- Anyway.

He only saw MacKenzie that one time, he said.

Didn't get her phone number and--

- And I didn't offer my number.

I generally don't give out my number.

- And that was that, he said.

He didn't expect to see her again.

But just 3 weeks later, MacKenzie was missing.

And Rob said the friend who was with him at the bar

that night made the connection.

- He just mentioned to me casually,

"Hey, you know that girl we met at the bar, uh,

"that's the girl that went missing."

- Of course, Rob remembered the friendly college student.

And the secret she revealed to him that night.

- I don't know whether she was seeking approval

or just advice or recommendations and--

- How did she put it?

- Uh, she just said she was on a dating site

and looking for sugar daddies.

And I asked her which one and she said,

"Seeking Arrangements."

- Seeking Arrangement.

A website designed to connect young women

with prosperous older men.

Rob knew a lot about dating sites.

He's a PI, remember.

And he figured if MacKenzie was missing,

that might just have something to do with it.

- I went straight home, got on the computer,

and got on to Seeking Arrangements.

And within an hour, 2 hours, I had found her profile.

- There she was, beachbaby96.

- What was interesting about her profile

was it was just very authentic and honest.

Uh, she wasn't really hiding who she was.

She was pretty specific about, you know,

she's a 23-year-old grad student at the U,

studying kinesiology. California girl.

You know, likes to drink wine.

Likes to go out. Likes to travel.

Looking for somebody to, you know, do that with.

- A little more PG than some of them, maybe?

- Yeah.

- Soon as he found it, he sent a screen grab

of MacKenzie's profile

to the Salt Lake City Police Department.

- This was definitely another avenue that we had to look at

and, you know, track down anybody

that might have been in contact with her.

- MacKenzie, it appeared, had compartmentalized information

about her life.

The plane ticket to Las Vegas, for instance, had been paid for

by a man she met through Seeking Arrangement.

And a $300 deposit to one of MacKenzie's back accounts?

- That was from one of her other dates

that she had been on that she'd received a-a payment from.

And that was prior to her going over to her, uh,

grandmother's funeral.

- Her friend Ashley said she didn't have a clue.

- I didn't know anything about her being on that site.

- She didn't talk about it.

It wasn't a-- like a subject of conversation.

- Not with me.

- MacKenzie's friend Kennedy wanted to avoid

the subject altogether.

But she acknowledged that Seeking Arrangement

is well-known on campus.

- This site is not unfamiliar to a lot of women in college.

- Everybody knows about it.

- Everybody knows of this site.

- Seeking Arrangement was founded in 2006

by a self-proclaimed nerd and MIT grad named Brandon Wade.

He declined our interview request,

but in this 2016 "Today Show" story,

Wade said he came up with the idea as a way

to meet young women.

- The average sugar baby is roughly 27-years-old.

Fifty percent of them are college students.

They're ambitious. They're beautiful.

Um, and they're on the website

because they want to find somebody who's successful

who's going to actually help them or spoil them.

- I think we're living in a culture

where it's much more accepted and embraced for women

to be up front about what they need and want.

- Journalist Maryella Mastoff writes about sex and culture

and sees sugaring as a form of female empowerment.

- And to hold power in a way that's open,

that is less stigmatized than it has been in the past.

- Mmm-hmm.

So, they would see this as holding power?

- I see it as very powerful, yes.

- How-- Explain that a little bit.

- Anytime you go into a relationship of any kind

saying "This is what I need and if you can't give me this,

"I'm going to move on," is a powerful thing to say.

- There is some debate about this.

Whether it actually empowers young women

or exploits the innocent.

- I mean... [sighing]

a lot of people who go into it are, like,

seriously so blind to, like, the whole reality

of what it is, you know?

- Like MacKenzie, Tasia Larkin

from Salt Lake City had a Seeking Arrangement profile.

But unlike MacKenzie, Tasia told us she was anything

but a newbie when we spoke to her in 2019.

At the time, the 20-something had been

with a sugar daddy for 6 months.

He was 63.

- Do you mind telling me how much he pays you?

- My allowance is $1200 a month.

Tasia told us it took her a long time

to find an arrangement.

- You have to fish through all of those guys who, like,

literally, they're like, "Let's meet up at a hotel,

"have sex, and I'll give you money."

And I'm like, "That's a prostitute."

- Shades of gray can be confusing for anybody,

said Tasia.

Let alone a novice on Seeking Arrangement.

- I've seen girls who have had sugar daddies.

They're not even the same person after it.

- Do you read, um, MacKenzie's, uh, profile?

- Yes, I did.

- She came from a very sheltered sort of upbringing.

Would that have made it more dangerous for her?

- Oh, most definitely.

- Yeah?

- Going into it blindly

is not something I would recommend.

- No.

- Like, at all.

- Welcome to "Let's Talk Sugar."

This episode is all about getting ready

for your sugar date.

- Seeking Arrangement does make what they call

"Let's talk sugar" videos that offer up advice

to novice sugar babies,

giving tips on everything from how to ask for an allowance

to what to pack in your purse.

Perfume, they say, and pepper spray.

- Not that you'll need it on your date,

but going out looking hot is always a risk.

- Did MacKenzie watch the videos?

We don't know.

But one of her decisions, said Tasia,

betrayed her lack of experience.

- Why would you meet in the middle of the night

in a park?

- And there was something else.

Whether MacKenzie did it or the person she met,

we don't know.

But remember, right after the Lyft driver

dropped her off at the park,

someone turned off MacKenzie's cell phone,

which happens to be contrary

to Seeking Arrangement's most important rule.

- You never want to get stuck phoneless.

That's your lifeline.

- Before her electronic lifeline goes silent,

MacKenzie is busy texting.

Investigators are determined to follow those cyber clues

wherever they may lead.

- We've got an IP address that comes back to his residence.

- Tracking text messages.

- He said, "Well, I have an open Wi-Fi

"because I run an Airbnb business.

"And so, it could be anybody from here."

- Did he run an Airbnb business?

- And a tip from a concerned neighbor.

- She described it as just being a really offensively smoky

and very odorous.

- What was it like for you when this discovery was made?

- It was just a sinking feeling, really.

**

- Detectives in Salt Lake City were trying to find out if

MacKenzie Lueck's disappearance was voluntary or not.

Remember the flight she was supposed to be on

to Los Angeles?

They found out it had been paid for by a sugar daddy.

But remember, MacKenzie wasn't on that flight.

And they found out she wasn't on the one to Vegas, either.

- It was at that point that we were able to say, okay,

we've got enough here that we build our probable cause back up

and really kick in and start serving

some search warrants again.

- And off the detectives went, in search of the mystery person

MacKenzie was texting the night she vanished.

- With a 206 area code.

Conversations going well before she left LA

to all the way to where she ended up in Hatch Park.

- That digital trail eventually led them to a Wi-Fi router

at this Salt Lake City house,

owned by a man named Ayoola Ajayi.

AJ.

Ex-national guard.

Successful tech worker. Part-time model.

Police knocked on AJ's door.

Talked with him and found he was friendly. Helpful.

Sure, he said, he had girlfriends.

But MacKenzie?

They showed him a photo, and he...

- Told them he'd never seen that lady before.

- So, why, then, the police asked,

did MacKenzie get texts routed through AJ's home Wi-Fi system?

- He said, "Well, I have an open Wi-Fi

"because I run an Airbnb business.

"And so, it could be anybody from here."

- Did he run an Airbnb business?

- He did.

He rented out the two bedrooms down

in his basement for Airbnb.

- They looked around.

Saw nothing amiss.

And left.

And then, that same evening, AJ stopped by the police station

to say he'd discovered something.

Turned out he had texted with MacKenzie Lueck

the night she'd disappeared.

He'd forgotten, he said, because MacKenzie was the one

who reached out to him, without identifying herself.

Maybe, he said, she'd seen his Seeking Arrangement profile.

Said he had no idea who it was.

But she'd blew him off, he said.

Ghosted him.

So, he forgot all about her.

But he told that story with so much confidence.

Too much, maybe?

- We had two different things now.

We've got an IP address that comes back to his residence,

and now we know he slowly had contact with her.

- Except there was no proof MacKenzie had been abducted

by AJ or anyone else, for that matter.

So, he was free to leave.

But before doing so, he gave the detectives

his cell phone number,

just in case they needed to get hold of him.

A cell number actually registered in his name.

Remember, police didn't have that before.

They just had that bogus 206 number

used by the texting app.

So now, with AJ's personal cell number,

they could get a search warrant for his call records

and tracking data. And 2 days later--

- We got the confirmation back from the FBI

that MacKenzie's records were showing her going

from the airport to Hatch Park and AJ's records

were showing going from his residence

and also meeting up at Hatch Park

at the exact same time.

- And that was enough to get a warrant to search AJ's home,

where investigators noticed a mattress was missing

from the bedroom.

And there was the strong smell of bleach.

They also spoke with a concerned neighbor--

her face blurred in this police video--

who wanted the police to know that AJ,

the week before, had started an illegal backyard trash fire.

- And she described it just being a really offensively smoky

and very-very odorous.

- Debris even flew into the neighbor's yard.

- It looked like maybe they were clothing.

Pieces of like, maybe fake leather, vinyl, something.

We weren't sure what it was.

- What was it like for you when this discovery was made?

- I don't know how to describe it.

I mean, it was just a sinking feeling, really.

I mean, we-- it's like we wanna know what happened,

but we also don't wanna know what happened.

Because if it's what we think happened,

then we don't wanna know that happened.

If that makes sense.

- That was probably the hardest part

in the investigation is watching him

walk out the door that night.

- Hard for detectives, but it gave MacKenzie's friends

reason to hope.

- Maybe MacKenzie was still alive and he was hiding her,

because the police let him go.

- I mean, you look at his profile pages on these sites

and he comes across as a gentleman.

- When "Dateline: Secrets Uncovered" continues.

**

Welcome back.

MacKenzie Lueck was secretly texting a man who went by AJ.

While AJ told police he never met MacKenzie,

cell phone tracking data placed them together

at the very hour she vanished.

Investigators had a suspect in their sights,

but still no idea where to find MacKenzie.

Now, with the conclusion of "The Waiting Car,"

here's Keith Morrison.

- Police looking for MacKenzie Lueck

had heard a disturbing story from a neighbor

who said Ayoola Ajayi had set a suspicious fire.

The neighbor had found debris in her backyard.

So, they looked in AJ's backyard

and found something else disturbing.

A freshly-dug patch of soil.

They called in a cadaver dog which gave

the unmistakable signal-- human remains.

AJ, who'd been calmly watching it all from his driveway,

was taken into custody.

- We have him 10-82.

- A team from the crime lab spent the night

digging up the backyard.

- They found more burnt clothing.

Purses or backpacks.

And then, down towards the bottom of the-the dig site,

there was a very burnt and damaged iPhone.

And the medical examiner identified human tissue.

- Just fragments, mind you.

They couldn't be certain who or even what they had exactly.

- We had these tissue samples or pieces.

And so, in order to charge somebody or arrest 'em,

that needed to be confirmed

and we knew that was gonna take time.

- So, without solid proof a murder had been committed,

they once again, reluctantly, let AJ go.

- That was probably the hardest part

in the investigation is watchin' him

walk out the door that night.

- MacKenzie's friends heard he was released

and they took it as a sign of hope.

- That maybe MacKenzie was still alive

and he was hiding her,

because the police let him go the next day.

- Then, at daybreak, detectives got a call

from the state crime lab about the remains

found in the backyard.

- They were able to identify that as being consistent

with MacKenzie.

- The SWAT team took AJ into custody

and police called a press conference

to announce his arrest.

- We are filing charges of aggravated murder

in the homicide of MacKenzie Lueck.

- Kennedy was watching on her cell phone.

- I-I almost blacked out or something.

I dropped my purse, my phone,

and I dropped to the ground on the street.

And I was just bawling.

I just couldn't even believe it.

I still can't believe it.

- But the detective work was not done.

Although they found human tissue in the firepit

and linked it to MacKenzie, they had not found her body.

So, the investigation continued.

And once again,

AJ's personal cell phone gave them away.

Remember when he first spoke to police about MacKenzie?

Well, the very next day his cell phone pinged

its way up into these mountains.

- About 2 hours north of here, up to Logan City.

And then goes partially up to the canyon.

And then returns back to Salt Lake City

a couple hours later.

So, that was odd to us.

- Had he, a nervous killer, exhumed her body

from that backyard fire pit to rebury her up here?

They set off to search Logan Canyon.

- And it took us a better part of the day

until we-we found her.

- That's gotta be another tough part of your job.

- It was horrific.

It was a-a sight that none of us wanted to see.

- The search for MacKenzie was over.

But the investigation was not.

In the weeks following, a woman came forward to say

she'd been sexually assaulted by AJ a year earlier.

- At AJ's residence, the same residence

where MacKenzie was killed.

- She said she met him through a dating app.

A religious one.

AJ was charged with aggravated kidnapping

and forceable sexual abuse in that case.

The evidence was tightening around him.

Evidence of what he did to MacKenzie was growing.

And finally, October 7, 2020,

Ayoola Ajayi pleaded guilty to murdering MacKenzie Lueck.

And as part of his plea deal,

he admitted he thought about killing MacKenzie

and then he planned the killing of MacKenzie.

A thoroughly pre-meditated murder.

- That he knew that he was going to murder MacKenzie

before-before she even touched down at the airport.

- He kind of selected her as his victim.

- Correct.

- Was there any explanation at all of what his motivation was

to do that? - None.

He never offered any reasoning of why.

Or even how.

- Ajayi also pleaded guilty to sexually abusing

his first victim.

He was sentenced to life without parole.

Oh, and one more thing, said the detectives.

He was active on the Seeking Arrangement site

right up until he was arrested.

- Even after we had made contact with him,

he was still on that page,

still trying to get a date.

- We don't know why, you know?

Some selfish jerk used his position on a--

on a dating website

to somehow ensnare this bright, pretty woman

and for what?

- I mean, you look at his profile pages on these sites

and he comes across as a gentleman.

Somebody that he truly isn't.

And that's the whole cautionary tale

is you never know,

are they actually who they say they are.

- Always, she'd been surrounded by people who loved her.

Worried about her. Cared about her.

MacKenzie Lueck was an innocent.

Setting out, if only for a moment,

to explore new possibilities.

Unaware that in the world she was entering,

the innocent can also be prey.

- That's all for this edition

of "Dateline: Secrets Uncovered."

I'm Craig Melvin. Thank you for watching.