A cell phone stolen from a 90-year-old Southwest Philadelphia woman during a push-in robbery and beating late yesterday led police to her alleged assailant today, officials said.

The robbery occurred about 11:30 p.m yesterday after the victim left the door of her home on the 2100 block of Carroll Street slightly ajar. She placed a brace behind the door to let air circulate, said Lt. John Walker of Southwest Detectives.

"She can't afford air conditioning," he said.

Walker said a woman appeared at the door and told the older woman that her daughter - with whom the victim had just hung up the phone - had been hurt.

Realizing the woman at her door was lying, the victim called out the name "Robert" and the assailant barged in, Walker said. The attacker punched the victim, grabbing her purse and cell phone, and then threw her on the couch, breaking her ribs.

The woman is expected to recover from her injuries, police said.

After the theft, Walker said, a friend of the victim's grandson started texting the stolen phone, saying that the woman was not doing well and that he needed the phone to get needed medical information. He also offered money for its return.

"He was trying to appeal to her emotions," Walker said.

The friend set up a meeting - and police took into custody a 17-year-old girl who had the phone, Walker said.

He said the girl told police that her mother had given her the phone. Detectives arrested the 35-year-old woman about 9:30 a.m. today, and she was expected to be charged with aggravated assault and robbery.

Contact staff writer Joseph Gambardello at 215-854-2153 or jgambardello@phillynews.com.