QUARRYVILLE, Pa. (AP) — A man facing trial on child sexual assault charges fatallystabbed a woman and her 16-year-old daughter "to silence them" because they were set to testify against him, a prosecutor said Friday, calling it an "absolute attack on the system."

Leeton Jahwanza Thomas is also accused of stabbing the woman's 15-year-old daughter in the rampage early Thursday, leaving her hospitalized in critical but stable condition, authorities said. A 13-year-old daughter wasn't home at the time.

"It's an absolute attack on the system, which is an attack on all of us," Lancaster County District Attorney Craig Stedman said at a news conference Friday. "Clearly one of the most disturbing crimes we've had. It's a nightmare."

Thomas, who goes by the nickname "Pie," was charged in April with molesting the 13- and 16-year-olds at his home in December 2013, according to case documents.

An upstairs neighbor who called 911 on Thursday after hearing screams said the 15-year-old immediately identified Thomas as the culprit, according to an affidavit of probable cause.

"Pie did it," she told neighbor Jennifer Hershey, according to the affidavit.

The girl told Hershey she had known Thomas her whole life, and they had spent time at each other's homes. Her mother was friendly with his wife, Stedman said.

"It's not a coincidence he targeted this residence," Stedman said. He believed the motive to be "retaliation — to silence them."

Thomas, 37, is charged with two counts of criminal homicide and one count each of attempted homicide and burglary. He is jailed without bail pending a June 22 preliminary hearing. No lawyer was listed for him in court records Friday.

Hershey's father, Robert Ulrich, told The Associated Press that Thomas has been battling medical problems for about two years that left him partially blind, an illness that a relative of Thomas' wife described to the LNP newspaper as a pituitary brain tumor.

He had once been a talented carpenter and is a married father of four, Ulrich said.

The medical problems seemed to weigh on Thomas, Ulrich said. The Thomases rent their home from Ulrich.

"He was always a nice guy. Personally, I think everything got to be too much for him," Ulrich said at his farm, situated between the Thomas and Hershey homes.

He said his daughter let the victims use her basement apartment. The mother worked part time in a notary office but struggled with diabetes, Ulrich said.

A lawyer representing Thomas in the sexual assault case was said to be out of town and did not immediately return a telephone message. No one answered the door at his rented home on a dairy farm, which has a backyard pool and trampoline.

"It's just unbelievable. A nice friendly neighbor like that, doing something like that. It's just unbelievable," neighbor Ben Stoltzfus, an Amish farmer, said as he loaded kale into a wagon.

Stedman vowed to consider seeking the death penalty despite Gov. Tom Wolf's moratorium on executions.

Court records showed that Thomas posted $5,000 bail on April 18 while facing charges of aggravated indecent assault involving children. The case was sent to a trial court May 22.

A formal arraignment in that case was scheduled for June 26.

Troopers said they were called to the home in a rural area about 70 miles west of Philadelphia at around 2:20 a.m. and found the injured 15-year-old hysterical and covered in blood.

They found the two dead victims while searching the home's basement. The hardwood stairs were covered in blood, and a window was pushed up with the screen removed and propped up against the outside of the home, according to the affidavit of probable cause.

"There appeared to be evidence they tried to escape," Stedman said.

Police led by a K-9 unit tracking Thomas' scent arrested him at his home a few minutes later. He was wearing a green bathrobe, and it appeared that the shower had recently been used, they said.