NASHVILLE, Tenn. — Former NFL star Steve McNair was shot dead in his sleep last week by a 20-year-old girlfriend distraught about mounting financial problems and her belief that he was seeing someone else, police said yesterday.

Sahel Kazemi "was spinning out of control" when she shot McNair four times as he dozed on a sofa early Saturday, then turned the gun on herself, Police Chief Ronal Serpas said.

Interviews with friends revealed that she was making payments on two cars, her rent was doubling and she suspected the married McNair was having a second affair with another young woman.

She told a friend on Friday that "My life is a ball of s— and I should end it," Serpas said.

Police earlier had labeled McNair's death a homicide, but waited for further tests and the revelations about Kazemi's personal problems before concluding that she pulled the trigger of a 9 mm semiautomatic pistol in a condominium McNair rented with a friend.

McNair, 36, a quarterback for the Tennessee Titans most of his career, met Kazemi six months ago at a sports cafe where she was a waitress and his family often ate. She seemed happy and eager to build a life with him, but something went wrong.

"We do know that she was clearly sending a message during the last five to seven days of her life that things were going bad quickly," Serpas said, though there was no indication she told anyone she planned to harm McNair.

Serpas said detectives learned that Kazemi recently found out about another young woman she thought McNair was romantically involved with.

Serpas said police believe McNair was asleep when he was killed because there were no defensive wounds. After shooting McNair in the head, Kazemi apparently shot him twice in the chest before shooting him again in the head.

She then shot herself.