Seven of Mary Bartel’s neighbors had been found dead by the time the stranger knocked on her door.

Jewelry and other valuables were missing from their apartments at Preston Place Retirement Community in Plano, but police and paramedics said their deaths must have been from natural causes, like heart attacks.

And though a stranger had been spotted on the property and fliers were posted warning residents about him, no one suspected he was robbing and killing the women until he visited Bartel.

Billy Chemirmir, 48, was arrested the next day, accused of forcing his way into her apartment, trying to smother her with a pillow and stealing her jewelry. He has since been charged with 18 counts of capital murder in Dallas and Collin counties.

Police have long said a woman who survived an attack in Plano helped lead them to Chemirmir, but they hadn’t identified her publicly, though Bartel’s name appears in court documents identifying her as the surviving victim.

The Dallas Morning News has not named her until now either, because she was a surviving victim of the crime and at the request of families of other victims.

But her family has now published a book about her life, publicly acknowledging for the first time her role in cracking the case.

The book details the attack, how Bartel helped police finally realize women were being killed in their homes and independent living facilities, and how the attack affected her mental and physical health in her final years.

Bartel died in February of last year at the age of 92.

“She played a good role in stopping a serial killer,” said Rick Bartel, Mary’s son who helped publish the book. “She thought that, you know, maybe she was saved so that she could save others.”

‘Don’t fight me’

After her husband’s death in 2015, Mary Bartel kept a regular routine. She went to early-morning Mass every day and to work out with friends at Preston Place, an independent living community.

The morning of March 19, 2018, was no different, according to her account in the book her family published. She woke at 4:30 a.m., drove herself to and from Mass, called her sister-in-law to catch up and got ready for her exercise class.

Then came the knock on the door.

“Go to the bed,” the man who knocked said, according to police reports. “Don’t fight me.”

He shoved Bartel onto the bed and placed a pillow over her face. She reached for a medical alert button but lost consciousness before she could press it.

Her workout buddy came to the door a few minutes later and found it ajar. She screamed for help, and another neighbor called 911.

Bartel was revived and taken to a hospital, where a police officer asked what had happened. She told him about the man who had come into her apartment and said she was missing jewelry.

The officer suggested she was confused. Maybe she hit her head, he told her sons at the hospital, and suggested that her neighbors stole the jewelry. Still, he called Plano Detective Paul Martinez to interview her as well.

When Martinez asked what was missing, she said the intruder may have taken cash. She promptly rattled off exactly how many bills and in which denominations had been in her purse.

Through a spokesman for the Plano Police Department, Martinez declined to comment this week, but according to Bartel’s account, that was the moment he realized that she wasn’t confused and that her story about the intruder probably was reliable.

Chemirmir’s arrest

Police searched through similar incidents and found a report of a suspicious vehicle — a silver Nissan Altima — that had been reported at other senior living communities in the area. Its owner was Billy Chemirmir.

Plano police waited outside his Far North Dallas apartment the next day, and after they saw him toss a jewelry box into a trash bin they arrested him for the attack on Bartel.

The Plano officers found the jewelry box in the trash and a name: Lu Thi Harris.

Plano officers contacted Dallas police, who went to check on Harris. She was found dead in her home, with lipstick smeared on a nearby pillow.

Chemirmir was charged with capital murder in Harris’ death, and with two attempted capital charges: one for the attack on Bartel, and one involving another woman who identified Chemirmir as the man who attacked her the previous October in Frisco.

Chemirmir has since been charged with 17 other counts of capital murder and is in the Dallas County jail, with bail set at $17.6 million.

A Kenyan immigrant with permanent resident status, he says he is innocent. He faces life in prison without parole. His first trial, for Harris’ death, is set to begin Nov. 12 in Dallas.

Video deposition

After the attack, Rick Bartel said, his mother’s health deteriorated quickly. She began slowing down, and didn’t deliver the readings at Mass as often.

Three months later, she fell at Preston Place, breaking her hip and fracturing her femur. After surgery, she was forced to move into a rehabilitation center and later to a nursing home.

According to the book, she also went to a psychologist to discuss the effect of the attack on her mental health.

That summer, because her health was failing and attorneys knew a criminal trial was probably years away, she recorded a video deposition that could be played at Chemirmir’s trial.

According to the family’s book, Chemirmir’s attorney and prosecutors questioned her for two hours while Chemirmir watched a video feed from jail.

Bartel said she couldn’t identify Chemirmir, according to the book. Instead, she told the attorneys about what she remembered from the attack.

According to the book, Dallas County prosecutors told Bartel and her family that her testimony probably would be used during sentencing — not the phase of the trial to determine guilt or innocence.

Because Dallas County District Attorney John Creuzot announced recently he would not seek the death penalty for Chemirmir, the punishment for a capital murder conviction automatically would be a life sentence so there would not be a sentencing phase in Dallas County.

Bartel’s recorded testimony, then, would likely go unheard unless Collin County prosecutors choose to take the case to trial and seek the death penalty.

Honored as ‘Citizen Hero’

In November 2019, Plano police recognized Bartel with a Citizen Hero award. Police spokesman David Tilley said the award is given to citizens who help detectives in criminal investigations. In an informal ceremony, the department thanked Bartel for her help in solving the case and presented her with a plaque.

“Her involvement in this case was crucial,” Tilley said this week. “Her role in this investigation was huge and definitely something we were very appreciative of.”

In her remarks at the time, Bartel directed praise to her friends and family for helping her survive the attack. She also praised Plano’s quick response and arrest of Chemirmir after she shared her story.

“It is frightening to hear the crime spree attributed to one person,” she said.

Still, according to the book, in her final months Bartel said she forgave Chemirmir and began praying for him nightly. Her family said that kind of grace was a lifelong trait.

“Not forgiving someone is like drinking poison and waiting for the other person to die,” Rick Bartel wrote in the book. “We expected forgiveness, but it was still somewhat shocking to hear her say she forgave Billy Chemirmir and that she prayed for him every day.”

Mary Bartel died Feb. 27, 2020, at an assisted living facility in Carrollton, just a few days before her 93rd birthday.

“She lived 91 years without taking down a serial killer, so that wasn’t the ultimate meaning of her life,” Rick Bartel said. “But, you know, we were obviously proud that she played an important role there.”