20/20 revisits a love triangle that led to a murder-suicide

Jennair Gerardot’s husband’s affair became an obsession for her that culminated tragically in murder and suicide.

She placed tracking devices on the cars driven by Mark Gerardot, to whom she’d been married for 24 years, and Meredith Chapman, the 33-year-old woman who’d hired him to work at the University of Delaware and with whom he was having an affair. She sewed listening devices into Mark’s clothes to secretly record his conversations when they were apart.

One of those recordings captured Jennair’s rising insecurities.

“You don’t find me appealing,” Jennair, 49, told her husband, according to the audio obtained by ABC’s 20/20 for an episode about the case airing Friday at 10 p.m. ET. (An exclusive clip is above.) “You don’t find me attractive. You don’t want me anymore. You don’t even like me. You are miserable.”

Referencing Chapman, she said, “She lights your fire, she makes you feel young. You’re excited, it’s all fresh. You’re getting to know each other and you are in love with her … ”

Jennair Gerardot, at left, and Meredith Chapman
| Credit: Instagram; Facebook

On April 23, 2018, according to police, Jennair donned a wig and rode the train from the couple’s home in Delaware to Pennsylvania, where she broke into the Philadelphia Main Line residence where Meredith, who was estranged from her own husband, lived alone.

There, after cleaning up the glass she’d shattered while entering the front door, Jennair lay in wait to shoot and murder Meredith as she walked in the door. Then Jennair turned her gun on herself.

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Mark, who arrived at the home out of concern for Meredith after receiving troubling texts from his estranged wife who’d blown off a dinner date they’d made for that night, was outside about 7 p.m. to meet arriving officers after finding the two bodies inside.

Police who recovered a series of text messages and emails written by the killer said they pointed to revenge as Jennair’s motive.

Mark Gerardot
Mark Gerardot
| Credit: 20/20

Mark earlier had confessed the affair to his wife, saying the two had begun counseling in what Mark believed was a step toward an amicable divorce as he continued his romantic involvement with Meredith.

Meredith, meanwhile, had started a new job as an assistant vice president at Villanova University, where she worked at the time she was killed. She was separated from her husband Luke Chapman, a former Newark city councilman, according to the Philadelphia Inquirer.

“You had a man who’s married who’s having an affair with this other woman. His wife knew that. This was a calculated attack,” Radnor Township Police Superintendent William Colarulo said at a news conference after the murder. “She broke into the house. She was lying in wait, and then she shot herself. There were emails and text messages indicating what she planned to do.”

“I broke her heart,” Mark tells 20/20 anchor Amy Robach about his wife. “My regret comes back to making her feel like she had no other choice.”

The 20/20 episode airs Friday (10 p.m. ET) on ABC.

If you or someone you know is considering suicide, please contact the National Suicide Prevention Lifeline at 1-800-273-TALK (8255), text “home” to the Crisis Text Line at 741-741 or go to suicidepreventionlifeline.org.