By Syma Chowdhry, Elizabeth Hur

PHILADELPHIA (CBS) — Philadelphia homicide investigators say a mother and son found dead in their burned out apartment on Howell Street Saturday is being ruled a double homicide, and now, sources say, authorities are questioning the woman’s boyfriend.

Police say the woman, Atlanta Deveney, 35, was choked and beaten, and her child, Elijah Rosado, 12, was stabbed in the neck and chest before the apartment caught fire.

The person of interest is 25-year-old Carlos Rivera, Deveney’s boyfriend. Sources tell Eyewitness News Rivera was taken into police custody for questioning Monday night.

Captain James Clark says of Rivera, “Yes very, very abusive, he was very much known to police.”

Rivera has an active arrest warrant out for armed robbery.

“But unfortunately she (Deveney) continued to deal with him.”

Rivera, Deveney and her son had moved into the apartment just a few days ago.

Questions still surround what led to the attack.

Clark says, “One theory is that he was physically assaulting the mother and the son came in and tried to come to her aid and with that he pulled out a knife and violently stabbed and killed the little boy.”

Police say Rivera was blocking neighbors from helping after they smelled smoke.

“As neighbors were outside trying to put the fire out, he is telling them don’t go inside, I’ll go in. I’ll take care of it but he never did,” Clark says.

So far, no charges have been filed against Rivera.

Watch & Listen LIVE