PHILADELPHIA (CBS) — Police sources say the person of interest in the fatal stabbing of his foster mother knows two missing people through foster home placements. Investigators have classified 20-year-old Jimmy Mao and 16-year-old Jacob Merritt-Richburg as “endangered.”

Jimmy Mao, left, and Jacob Merritt-Richburg. (credit: Philadelphia Police Department)

A 17-year-old boy is the person of interest in the stabbing death of 64-year-old Renee Gilyard, whose body was found in a bathtub inside her East Germantown home, shortly before 1:30 a.m. Wednesday. Gilyard is the mother of a Philadelphia police officer. Police say the teen is believed to be the last person to see Gilyard.

(credit: Facebook)

Police also say the teen is the last person to have seen Mao before he disappeared. SVU detectives have been searching for Mao since Jan. 2 and they consider him to be in danger. The Southwest Philadelphia man was last seen Dec. 29.

Police are investigating Mao’s disappearance as a kidnapping after a family member received text messages demanding money.

“It was originally considered just missing, then on Jan. 7, Jimmy Mao’s brother started receiving texts demanding ransom for his safe return,” Philadelphia Police Capt. Mark Burgmann said. “We did investigate that, however, based on the nature of the demands, it did not seem credible at the time. However, we continue to investigate as if it was and still do, a kidnapping investigation.”

Burgmann said they interviewed the 17-year-old teen but “he could not shed further information about” Mao’s whereabouts.

Investigators say they are also looking for 16-year-old Jacob Merritt-Richburg, of North Philadelphia’s Francisville section.

Jacob, Mao and the person of interest in Gilyard’s stabbing death all know each other from Department of Human Services placements, police sources say.

Investigators say they believe Jacob has some of Mao’s property, but they wouldn’t say what.

“During our investigation, we also came across someone named Jacob Merritt-Richburg, a 16-year-old from 1800 Vineyard Street,” Burgmann said. “We believe he is some type of acquaintance of Jimmy Mao and we believe he may be in possession of property that belonged to Jimmy Mao.”

The 17-year-old is being questioned by Philadelphia homicide detectives.

Investigators are feverishly trying to connect the dots between the two cases, that, as of right now, has detectives working nonstop.

If you have any information on Jacob or Mao, call police.