(09/29/10) BROOKLYN - Opening statements began this morning in Tianna Brown?s murder trial.

Brown was 15 years old when she was accused of stabbing her 16-year-old cousin to death two years ago.

Today's proceedings began with testimony from Brown's aunt, Marva Braithwaite. Braithwaite said she took Brown into her home after she had been having problems at her home. Brown?s lawyer says when she was 13, she was raped repeatedly and found out her grandfather was actually her father and that he had raped her mother.

Braithwaite said when she came home the day her daughter Shannon was killed, she was unable to unlatch her apartment door from the outside and found her daughter on the floor, covered in blood.

Brown's lawyer said she was diagnosed with post-traumatic stress disorder when she was 15 because of her problems at home.

The prosecution is expected to call police officers and medical experts next week. The judge expects the trial to last three weeks.