HILO >> The first of two trials starts with jury selection Monday for a man charged with beating a toddler to death and strangling the child’s mother almost nine months later. 

Police arrested 40-year-old Xavier Cortez Jr. in January 2011 on a first-degree assault charge when his girlfriend’s 18-month-old daughter was admitted to the hospital with breathing problems, The Hawaii Tribune-Herald reported. She died a week later at The Queen’s Medical Center in Honolulu.

Deputy Prosecutor Joseph Lee says Cortez killed 20-year-old Sommer Ferreira in September 2011 because she said she’d testify against Cortez.

Hilo Circuit Judge Glenn Hara allowed statements Cortez made shortly after the death to be admitted. Police Detective Robert Almeida said Cortez told him he was worried about Ferreira’s mental condition.

He was in the bedroom of the apartment he shared with her when he looked out the window and saw her leg hanging from the staircase. Almeida says Cortez told him he found her hanging by a sports bra from stair piping.

Cortez said the landlady helped him take her into the bedroom and perform CPR.

Defense attorney Stanton Oshiro said during cross-examination of Almeida that a bungee cord at the scene could have made the marks found on Ferreira’s neck.

Cortez goes on trial for Ferreira’s death Aug. 11.