Police say a single Pennsylvania mother of six young children was slain when she and her ex-boyfriend -- who fathered one of her children -- argued over money for diapers and baby wipes.

A man whom police called a person of interest in the shooting death of 28-year-old Marqua Wilson was located Tuesday evening, and named the suspect in her murder.

Markese Reese, 20, is to be questioned about the case.

"I turned myself in," he said as officers led him inside police headquarters.

However, a press release from police said that officers located him around 7:20 p.m. at the home of an acquaintance Pittsburgh.

Reese was arrested and charged with homicide Tuesday night.

Authorities said Wilson was found Monday with a gunshot wound in the head on the second floor of a townhome in a Pittsburgh neighborhood.

Police said Reese had stayed at her townhouse on the night before the shooting.

Witnesses told police they saw Reese running from the home around 1 p.m. Monday.

According to a criminal complaint obtained by WPXI, one witness inside the home said she heard a loud 'boom'.

"Shortly after, Reese came down the steps." 

"Reese stated 'Don't say anything…I need you to come upstairs…she's hurt…you know we were both fighting."

The paperwork also revealed why the pair had been fighting.

A witness told police Reese wanted money from Wilson for diapers and baby wipes that he brought to her.

Investigators searched for Reese Monday evening with the assistance of SWAT, but he was nowhere to be found.

According to the criminal complaint, police had talked to Reese on the phone to negotiate his surrender.

"...he uttered 'we were struggling over a gun and it accidently went off and I ran.'"

Police said Reese had agreed to meet them at a motel, but when officers arrived he was not there.

Despite what authorities said Reese told them on the phone, he took to social media late Monday night to say he’s innocent.

“That’s my baby’s mom, and I’m innocent. I love her to death,” he reportedly wrote on Facebook. “Everybody knows our history back in the day. We used to fight. I’m mourning more than anybody. (I) wasn’t even there and they know that.”

The estranged couple’s history dates back to 2013 and played out in court. Wilson obtained a temporary protection from abuse order against Reese twice, telling police that he beat her.

“I fear for my life and (the) life of my children, including the one we share together,” she wrote. “About a year ago, he beat me with a metal brook to the point I received nine stitches.”

Wilson’s family has yet to speak publicly but was seen gathered outside the crime scene Monday evening.