Law professor's killer stalked him 'like a shark circling' before ex-mother-in-law's murder-for-hire ambush

After leaving the gym, Dan Markel drove home expecting an ordinary day.

Instead, his killer was waiting for him.

As he arrived home, the prominent Florida State University law professor was talking on the phone with music teacher Stewart Schlazer about school options for his children.

Then the conversation took a terrifying turn.

"Can you please hold on a second? There's an unfamiliar person in my driveway," Markel said.

SLAIN DAD'S DAUGHTER KNEW ‘BLACK SWAN’ EX-BALLERINA SHOT HIM AFTER ONE CALL: 'SHE KILLED HIM, DIDN'T SHE?' Seconds later, Schlazer heard what he described as "a loud boom." "There are really eerie parts of those final hours," producer Lily Fletcher told Fox News Digital.

"You look at the CCTV footage, and it's a normal day.

Dan dropped off the kids at school, he's gone to work out at the gym, and then there's a Prius driving around the gym car park.

It never stops.

It's clearly waiting for him." "It's always reminded me of a shark circling," Fletcher said.

"There was something just so sinister and eerie during such a mundane part of his day, just going to the gym.

That really stayed with me.

That's a really chilling part, just watching that footage." Markel was shot in the head while sitting in his car in the garage of his Tallahassee, Florida, home on July 18, 2014.

The 41-year-old died the following day.