Big Pharma Researcher Stabs Romantic Rival To Death, Then Tries To Kill Husband

Murders A-Z is a collection of true crime stories that take an in-depth look at both little-known and infamous murders throughout history.

Sheila Davalloo was smart.

She landed a well-paying medical research job straight out of college. She had an affair, and neither her husband nor her boyfriend knew the other existed. She even murdered her boyfriend’s girlfriend and almost got away with it.

But, Davalloo’s smarts came up short when she tried to stab her husband to death and was captured by police.

Davalloo and her family immigrated to the United States in the late 1970s to escape the chaos and violence of the Iranian Revolution. She and her parents — medical and health professionals — landed safely in their new country and settled into the New York suburb of Yorktown Heights.

Like her mom and dad, Davalloo was a gifted student, but bowing to family tradition, she was married just out of high school. As a young newlywed, she enrolled at the University of Stony Brook in New York, where she earned a degree in biochemistry.

After college, Davalloo attended graduate school at New York Medical College. There, she met a fellow student named Paul Christos, and they began having an affair. When her husband, Farid Moussavi, found out about it, he and Sheila divorced. Despite the scandal, Paul and Sheila stayed together, and they were married in 2000.

They moved to Pleasantville, New York, the following year. Located just north of New York City in suburban Westchester County, it was a convenient commuting distance from both their jobs. Paul worked for Cornell University at its New York City campus, while Sheila landed a job as a research scientist at Purdue Pharma, located in Stamford, Connecticut.

Though things were going well for the couple, the heat of their once passionate affair grew cooler with each domestic accomplishment.

The two were living more like roommates instead of spouses, said Davalloo in an exclusive prison interview with “Snapped Behind Bars: Sheila Davalloo,” premiering Sunday, Dec. 1 at 6/5c.

In the summer of 2001, Davalloo met co-worker Nelson Sessler at a happy hour get-together after work. They soon began a sexual relationship, according to court documents. Sessler, however, had no idea the woman he was sleeping with was married.

In order to cover up her affair, Davalloo concocted a complicated subterfuge, fooling both husband and lover. To get rid of Christos for the night or weekend, Davalloo told him her mentally ill brother was visiting and would become upset if he knew she was married.

Christos actually helped his cheating wife remove any trace of his existence from their home, packing up clothes, toiletries and photographs, before going off to spend the night at his parents’ or one of his friend’s houses.

When Sessler would arrive to sleep over, he assumed Davalloo lived alone. 

“He believed she was separated, divorced,” former Westchester County Police Detective Alison Carpentier told a previous episode of “Snapped.” “Paul, literally, did that good of a job moving things out or Sheila would do that good of a job at hiding things.”

And Davalloo was not the only one with multiple romantic interests.

At the same time as she was seeing Sessler, he was dating another co-worker at Purdue Pharma named Anna Lisa Raymundo. Eventually, he would break things off with Davalloo and move into Raymundo’s Stamford apartment. Davalloo seemed to take it in stride, telling Sessler their relationship was just a summer fling, according to the Stamford Advocate newspaper.

Privately, however, Davalloo obsessed over Sessler and plotted to eliminate Raymundo. Among those she consulted about the relationship was her own husband. Christos testified that Davalloo spoke to him daily about a "love triangle" at work between her friends “Melissa,” “Anna Lisa" and “Jack.”

“She would constantly ask me why Jack would do this, what he was thinking and what 'Melissa' should do," Christos said, according to local newspaper the Norwalk Hour.

Davalloo told Christos she spied on "Anna Lisa" and "Jack" with “Melissa” and wanted to break into her apartment to look at photos.

On the morning of Nov. 8, 2002, Davalloo made her move. She entered Raymundo’s apartment and stabbed her multiple times on the face, neck and chest, one puncture wound reaching the back of her lung, according to the Stamford Advocate. Raymundo also suffered blunt force trauma to her head.

To throw authorities off her trail, Davalloo called 911 with a fake description of a male assailant.

“I think a guy is attacking my neighbor,” she can be heard saying on recordings of the call, obtained by “Snapped.” “I don’t know her name but she’s my neighbor and she lives in 105 … I saw a guy go into her apartment.”

Davalloo didn’t identify herself and hung up after fumbling Raymundo’s address. The 911 dispatcher called back and discovered the call had come from a payphone at a restaurant near the crime scene, according to court documents. The restaurant’s manager couldn’t recall seeing anyone at the payphone.

Responding to the 911 call, authorities converged on Raymundo’s apartment.

“They opened the door, and they walked in on a horrific, violent assault scene,” Stamford Police Captain Richard Conklin told “Snapped” in 2012. “The walkway from the front door was a bloody mess, things thrown about and knocked about.”

The apartment showed no signs of forced entry or a robbery. Conklin said crime scene technicians carefully swabbed up blood, believing the perpetrator’s DNA might be present.

“In an edged weapon assault or homicide, it’s very common for the hand to slip off the handle or over the hilt and to go down on the blade and the perpetrator cuts themselves,” former Stamford Police Detective Gregory Holt told “Snapped.”

A drop of blood was lifted from the bathroom sink, which detectives believed the killer used to wash up after the attack. Christos would later recall Davalloo had a deep cut on her hand around the time of the murder. She claimed it came from opening a can of dog food, according to the Stamford Advocate.

Sessler arrived at the apartment later that afternoon, completely unaware of what had happened. He responded calmly when informed of Raymundo’s death, which raised the suspicions of investigators.

He was brought in for questioning, but Sessler was cleared the following day when Stamford Police reviewed security records from Purdue Pharma.

“They have very good security cameras, security system, and they were able to show what time he punched in,” Conklin told “Snapped.” “He was at work when this assault took place.”

Following up on Davalloo’s bogus tip, authorities searched for a male suspect to no avail. They also sought out the 911 caller, who had claimed to be one of Raymundo’s neighbors.

“We canvass all the neighbors, but no neighbor in that area matches that voice,” Conklin said.

While police chased dead ends and phony leads, Davalloo used the occasion to renew her relationship with Sessler. She consoled him in his time of grief, and by January 2003, they were sleeping together again, according to court documents. Davalloo even used the same visiting brother ruse to send Christos away when Sessler was coming over to spend the night.

With her rival for Sessler’s affections out of the way, it was now time for Davalloo to get rid of her husband. It was a Saturday afternoon on March 22, 2003, when she suggested to Christos that they play a bedroom game to spice up their failing marriage.

One person would be bound and blindfolded, while the other touched them with different objects. The one wearing the blindfold would then have to guess what the object was.

"I heard her go down to the kitchen, and when she came up, she said, 'There is one last item, one last thing to guess’,” Christos later testified, according to the Norwalk Hour. “I felt her sit on me, then I felt a thrust like a heavy weight was on my chest, and then another thrust."

Davalloo had stabbed him twice in the chest with a paring knife.

Christos begged her to call 911, but his wife stalled for time, hoping he would bleed to death. Instead of calling emergency dispatch, she phoned Sessler and asked him to come over for dinner that night.

After almost an hour had passed, she agreed to drive Christos to Westchester Medical Center.

In the parking lot, she stabbed him a third time, nicking his heart, according to the Stamford Advocate. Christos managed to escape, and a group of bystanders who witnessed the attack called police.

Christos survived following open-heart surgery, and Davalloo was arrested for attempted murder.

Detectives in Westchester drove to Stamford to talk to Sessler after seeing Davalloo had called him in between stabbing her husband. Learning his girlfriend had recently been killed, they spoke with detectives working the Raymundo murder and discovered the two cases were connected.

“When we heard the 911 tape, I said to them, you know, ‘That’s Sheila Davalloo’s voice,’” Carpentier told “Snapped.”

In 2004, Davalloo was found guilty of attempted murder and assault for the stabbing of her then-husband Christos. She was sentenced to the maximum of 25 years in prison without the possibility of parole.

After slowly and methodically building the case against her, authorities in Connecticut arrested Davalloo in prison for the murder of Raymundo, according to the Stamford Advocate. The prosecution rested on two damning pieces of evidence — Davalloo’s voice on the 911 call on the afternoon of the murder, and the blood sample taken from the bathroom sink, which came back as a match to Davalloo.

She was ultimately found guilty of Raymundo’s murder and sentenced to 50 years in prison, according to the Stamford Advocate. Upon completing her 25-year sentence at New York’s Bedford Hills Correctional Facility for Women, she will be transferred to a Connecticut prison to begin her 50-year sentence.

To learn more about the investigation and hear exclusive prison interviews with Davalloo, watch “Snapped Behind Bars: Sheila Davalloo,” premiering Sunday, Dec. 1 at 6/5c on Oxygen.