A nephew of a 60-year-old Conshohocken woman was charged with first-degree murder and related offenses in the fatal stabbing Friday of his aunt, the Montgomery County District Attorney's Office announced Saturday.

Matthew Wertz Jr., 28, was arrested Friday in the stabbing death of his aunt, Catherine Wanamaker, in her home on the 900 block of Hallowell Street. Wertz was living with his aunt in her home.

At 5:14 a.m. Friday, Conshohocken police responded to a neighbor's call of Wanamaker screaming for help — "911, 911," she yelled — and a dog barking, according to the affidavit of probable cause in his arrest. Officers found the residence secure, looked through a window and saw a man inside, who then quickly rushed out of view. They had to force their way into the dead-bolted steel front door with a sledgehammer.

Inside the home, officers found Wanamaker dead on the living-room floor. She had been stabbed nearly 40 times, with wounds to her back, chest, face, head and neck area and with defensive wounds on her hands, according to an autopsy conducted by the Montgomery County Coroner's Office. Detectives found "a blood-covered kitchen knife" with about a 6-inch blade in the adjoining dining room, the affidavit says. 

Police on Friday also found Wertz kneeling several feet away from his aunt's body, with his back toward the officers. He refused commands to show his hands, was crouched over, had a knife in his hand and "appeared to be stabbing himself in the throat area with the knife," the affidavit says.

Officers ordered him to drop the knife, but he refused, prompting one officer to use a taser to disarm him, the affidavit says. Wertz was then taken to Lankenau Medical Center for treatment. After being discharged from the hospital, he was transported Friday to the Montgomery County Correctional Facility, where he remains in custody.

Detectives on Friday interviewed Wertz, who admitted stabbing his aunt, the affidavit says. "I did it, I was not in my right frame of mind when I did it," Wertz told detectives. He refused to say more.

Wertz's mother, Diane Wertz, was also interviewed by detectives Friday. She told them that her son had been living with her sister because her sister had offered to take care of him since he was disabled, the affidavit says. The document does not say what disability he had. Diane Wertz also told detectives that her son had just been released from the Montgomery County jail on Monday on another matter. 

She said her son abused heroin, painkillers, crack cocaine and "pretty much whatever he could get his hands on" and gets angry and acts out when "he needs drugs or wants to get drugs," she said, according to the affidavit.

Wertz was arraigned Saturday before Magisterial District Judge Henry Schireson. Bail was denied. A preliminary hearing is scheduled for 10 a.m. Dec. 29.

"This is a terrible tragedy. A woman opened her door to a relative who had just been released from jail, and in return she was brutally murdered," Montgomery County District Attorney Kevin Steele said in a statement released Saturday.

Wertz, court records show, had a history of drug-related and theft convictions.

The affidavit says Conshohocken Police Department records show police were contacted seven previous times for issues between Wertz and his aunt. Earlier this year, Wertz was charged with unauthorized use of an automobile after he was accused of taking his aunt's 2016 Chevrolet Equinox in April without her permission.

On July 20, police responded to a disturbance in which Wertz was having "a panic attack" and was threatening Wanamaker while holding a steak knife in his hand, the affidavit says. He was arrested on that date, court records show, but it is not clear if he faced charges in relation to the alleged threats.

Wertz, according to court records, appeared to have entered a guilty plea in court in recent weeks in the automobile case, but this could not be confirmed Saturday.

A voicemail left on his parents' home phone Saturday was not immediately returned.