CHICAGO -- Funeral services were held Saturday for Mya Lyons, 9, whose father found her dead on Tuesday.

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Relatives said police told them the girl was slashed in the neck and abdomen and had been sexually assaulted. Her body was found in an alley early Tuesday in the 8400 block of South Gilbert Court in the Auburn Gresham neighborhood.

A man, police said was a person of interest and not a family member of the girl was in police custody Friday, but no charges had been filed as of 3 p.m., according to a source.

NBC5's Lauren Jiggetts reported that the Chicago Sun-Times described the person in custody as a man in his 30s or 40s who might be mentally unstable. The man, who was not identified, was arrested Thursday night, and has apparently told police that he was in the alley Monday night.

He told investigators he is a scrapper -- someone who collects scrap metal -- to sell. He allegedly admitted to police he was in the alley and said that if had stayed longer, he could have saved her, according to the source, who said the person of interest might be mentally unstable.

The wounds on Mya's body were all on her right side torso area, leading investigators to believe the crime was committed by a left-handed person, and the person of interest is left-handed, according to the source, who said the man has a cut on his right hand that dental forensics investigators believe might have been caused if Mya bit him.

Investigators are in the process of obtaining a search warrant to look at items inside his home.

On Friday, Robert Lyon said he was hopeful that his daughter's killer had been caught.

"I'm hoping that whoever they have, that it is someone who truly should be there," he said. "I'm hopeful, because of the way that the investigation has been going as far as I know, that they have a very good suspect if not the actual person, and I believe that this is a case that will not linger forever -- there will be justice, and I believe that."

Chicago police would not confirm the Sun-Times' report, Jiggetts said.

"Several people are being interviewed, have been interviewed," said Steve Peterson, deputy superintendent of the Chicago Police Department. "The case is ongoing at this time, with the evidence being worked up."

Chicago police held a roll call Friday night at the place Lyons was found.

"There are some folks who might say -- that believe -- that we have lost of the streets of Chicago, and that the criminals have taken over. I would challenge all of you (the police officers) tonight to disprove them and go back and take control of the streets."

Mya lived with her mother, Erica Barnes, in Addison, but for the past three years was spending part of the summer with her father, Richard Lyons, in the 8400 block of South Gilbert Court.

At some point Monday night, the family realized she was missing.

"Everybody was like, 'Where is she?'" her father said. "We went looking for her and I found her in the alley. They dumped her in the alley" at the end of the block near his home, said Lyons, breaking down.

Lyons rushed his daughter to Jackson Park Hospital, where she was pronounced dead at 2:10 a.m. Tuesday, according to the Cook County Medical Examiner's Office.

An autopsy Tuesday showed she died of multiple injuries from an assault, according to the medical examiner's office, which ruled the death a homicide.

Calumet Area detectives are investigating.

Additional information provided by Chicago Sun-Times Inc.