Brittany Pullum describes the scene at a fire in the East Chatham neighborhood on Wednesday afternoon. (Posted on: Feb. 21, 2013)

Curtria Duncan had gone back to school to become a medical technician. Her mother Cherie Adams doted on her grandchildren.

Wednesday afternoon, the two were found stabbed in the bathroom of their apartment in the East Chatham neighborhood as firefighters put out a suspicious blaze.

Duncan, 24, was lying inside a bathtub and Adams, 43, was lying on the floor nearby in their apartment in the 8100 block of South Maryland Avenue, officials said.

Duncan died from "homicidal asphyxia," with multiple sharp force injuries a contributing factor in her death and Adams died from multiple sharp force and blunt force injuries, the Cook County medical examiner's office determined following autopsies. Both deaths were ruled homicides.

The apartment may have been set on fire to conceal the homicides, sources said. A large kitchen knife was found in the bathroom. No arrests have been reported.

"It hurts so bad," said Duncan’s sister Rochelle Pinex, 28, of Harvey. "Who could have done this and what for?"

Duncan had a 3-year-old son, Michael, but the boy was not home because he was visiting his father, Pinex said.

She said Duncan was studying to become a medical technician at Kennedy-King College, where she’d met a man who works at the school.

Pinex said Adams was her stepmother who had eight grandchildren who called her “Nana.’’

"She was changing her life around," Pinex said of Adams. "She was going to church three times a week and trying to spend more time with her grandchildren."

She described her sister and stepmother as people who “stayed to themselves’’ mostly.  “They don’t bother anybody,'' she said, sobbing.

Pinex said the women lived at the Maryland address for just under a year and rarely socialized, except for going to church and classes. “She’s a quiet girl,’’Pinex said of her sister.

Pinex, who has three children, said her 8-year-old daughter was looking forward to seeing Adams. “My kids, they loved their Nana to death,’’ she said. Her daughter was “begging” to go there for a weekend visit.

“She tugs at her (Adams’) heart and made her feel good,’’ Pinex said. “My daughter was her heart.’

“I’m trying to be strong,’’ Pinex said. “I can’t believe this tragedy.’’

chicagobreaking@tribune.com