Killer Motive

Look who's this?

Woo, her new Cadillac bike.

The McStays are the All-American family.

All Joey ever really wanted

was to be a father and a husband.

Summer loved her kids.

Until a horrific tragedy

unfolds.

So are you saying to yourself,

"How does an entire family go missing?"

Exactly.

It's like they went poof.

- What is there to be done when you don't even have a body

or evidence of a crime.

Why was the car by Mexico?

- It wasn't unusual for them to take off little mini trips.

Could this of been foul play?

There was no evidence,

there was no forensics,

they just have a mystery.

There are no answers

devastating the McStay's parents and siblings for years.

You can't believe.

No, this isn't happening.

You keep saying, "This isn't happening."

- Joseph's mother, Susan, speaks out

in a rare interview.

How did you celebrate holidays without your family?

I didn't.

About her agony,

and the unspeakable truth unearthed in the Mojave Desert.

- How did you learn that your family was found?

I'm Troy Roberts.

I've come to Southern California

to uncover what could motivate someone

to do something so gruesome,

slaughtering an entire family.

Why take the lives of these innocent children?

Oh.

The Mojave Desert...

46,000 square miles of the driest,

bleakest landscape in America.

It's here in the beautiful desolation of the Mojave

where the bright future

Joseph McStay built for his family

came to a heartbreaking end.

It's a horrific tragedy that hit home

for families throughout the country.

A story that begins with such promise

four decades earlier in Plano, Texas.

Joseph and his younger brother, Michael,

have a typical Texas childhood

filled with sports.

Their parents stay busy trying to keep up.

- You run one to a baseball game,

another one you're dropping off at soccer,

and then you're going back to baseball or vice versa,

and you're lucky to see 30 minutes of the last game.

And everyone seemed happy?

Oh, yeah, very much so.

When Joseph is in high school, his parents split,

and his mother, Susan, finds work

in Orange County, California.

Her boys make the move with her.

They liked living in Southern California?

- They felt, they felt I think a little more

at home in Southern Cal.

Joey was a surfer, Mikey was also.

And they're very outgoing kids.

They were always doing things outside our whole life.

I'd go dirt bikin' with them on 50-mile cross-country,

and they thought that was so cool

that mom was doin' it.

We did everything together.

As he grows into adulthood,

Joseph finds a another passion

as an artist and entrepreneur.

- He started making the fountains in his garage.

Handmade out of slate, and stone, and that,

and the water trickles down.

He called me and he said,

"Dad, I think I can do really good with this."

I said, "Do it."

- You encouraged his entrepreneurial spirit.

Mm-hmm.

Joseph calls his business

Earth Inspired Products.

So then he brings in Dan Kavanaugh,

at that time he was about 18.

And he was gonna set up the website and all that for Joey,

so that when somebody clicks on

you're the first company that comes up.

- Dan Kavanaugh surfed with Joey,

and he was a good friend.

In addition to Dan Kavanaugh,

Joseph brings on more help hiring Charles Merritt,

known to his friends as Chase

to help execute his vision and the build the fountains.

- Chase was a subcontractor that did the welding.

The business grows quickly.

Joseph sells fountains to beauty salons, hotels,

and corporate offices.

- And then he set it up to be international,

and was getting orders from other countries.

So how big of a business was this?

Their business was booming.

But something is missing in Joseph's life.

Something that gets filled

when he meets a real estate agent

named Summer Martelli in 2004.

Tell me about Summer.

Intelligent, pretty, um,

feisty.

She could go down on Bowery Street

and probably cuss with the best of the sailors.

They've been dating several months

when Joseph springs a surprise on his mother.

Obviously he was taken with her.

He just basically says,

"Well, Mom, I'm doing some stuff backwards,

she's pregnant."

She's pregnant.

When I very first met her, she was very nice,

very nice girl.

And they were really happy because

this was Summer's first child,

and Gianni looked a lot like Joey.

Joseph and Summer marry in November of 2007.

They welcome another boy that same year, Joseph Jr.

We called him Chubba.

- Chubba. - Yeah.

Where'd that come from?

- He had those chubby big thighs.

He could just go.

I'm gonna get you.

I'm gonna get you.

With Joseph's business booming,

the McStays moved to Fallbrook,

a community in San Diego County

known as "The Friendly Village".

There's the house.

This is the house?

I love this mountain right here to look at.

It's so cool.

There's the entrance.

Nice tile.

Everything's- - Papa.

- Light colors. - Papa.

Hi, you like all this big room in here?

Papa.

Joseph and Summer McStay have it all,

but in February 2010,

two months after the move to Fallbrook,

the mystery begins.

When was the last time you spoke to Joey?

February 4th,

that morning,

and he told me he was in hurry

'cause he had a lunch meeting.

Several days go by without a call or text

from Joseph or Summer.

- It wasn't unusual for them to take off on little mini trips

whether they'd go up to Big Bear or whatever.

So you're weren't alarmed?

Not in the beginning.

And then as the days went by, you start thinking

"Okay, something's not right here."

You start calling his cell phones, her cell phones.

- And then you ask your son, Mike, to do what?

- I had asked Mikey to go by the house.

February 13th,

nine days since anyone has heard from the family.

When Michael went the house, was there anything unusual?

Yeah.

Oh, get, get it, Bubba.

- The dogs are in the backyard, which is highly unusual

for them to be left out alone like that.

Michael also notices

his brother's Isuzu Trooper is gone.

The doors are locked,

Michael crawls through a window,

and he finds eggs rotting.

And some other fruits decaying.

Here's Summers prescription sunglasses.

What was going through your mind?á

- My first thoughts were something happened.

Are you saying to yourself,

"How does an entire family go missing?"

- Exactly, it's like they went poof.

There were some interesting theories

that your son was involved with a drug cartel.

I heard a lot of stories.

A peace sign.

- Did Joey and Summer have any enemies?

He had been arrested

for threatening to kill a neighbor and her daughter.

- In the period leading up to your son's disappearance,

was he having arguments with Dan over money?

- He had told me he wanted to buy Dan out.

- It must be getting frustrating at this point.