Benjamin Sebena, charged with killing his wife, Wauwatosa Police Officer Jennifer Sebena, has changed his plea to not guilty by reason of mental disease or defect.

There had been speculation that he would change his plea from not guilty to not guilty by reason of mental disease or defect, and point to post-traumatic stress disorders as the underlying cause. 

The plea sets up a two-phase trial, first for jurors to determine whether he is guilty, and then if found guilty, for them to assess his mental state at the time of the crime.

The trial is expected to begin July 8.

The charge against Benjamin Sebena, first-degree intentional homicide by use of a dangerous weapon, carries a maximum penalty of life in prison without possibility of parole. Sebena pleaded not guilty at his arraignment Jan. 24.

Jennifer Sebena was found dead just outside Wauwatosa Fire Station No. 1 in the Village, shot five times in the head. She had been on the police force for two years, and graduated from the top of her class at the MATC Police Academy. She had gone on solo patrol in July and had been assigned to the night shift only about a month before her death.

Benjamin Sebena quickly became a suspect and, after questioning, admitted in a statement to police that he had murdered his wife, according to the criminal complaint against him.

Benjamin Sebena, a wounded Marine veteran of the Iraq War, told investigators that when Jennifer came out of the fire station's north door, he stepped up behind her and fired two shots to the back of her head. The medical examiner's report shows that either one of those shots alone would have been instantly incapacitating and almost certainly fatal.

But, according to the criminal complaint, Benjamin Sebena grabbed his wife's service weapon and shot her three more times in the face – so that "she wouldn't suffer," Sebena told police. 

The last contact police dispatchers had with Officer Jennifer Sebena was at 3:29 a.m. They attempted to contact her again about 4:30, and when she failed to respond, a search located her body just minutes later.

Benjamin Sebena called the Wauwatosa Police Department at 6:35 a.m. to ask if Jennifer was all right, saying he had heard there had been an incident involving an officer. He was told Jennifer had been in an accident and that he should come to the station as soon as possible. Sebena did not ask what had happened to his wife.

At the station, when told Jennifer had been killed, a detective sergeant said Sebena did not ask how she had died.

Sebena was questioned at length on Christmas Eve and taken into custody Christmas Day.

Officer Jennifer Sebena was buried with full honors after a memorial service attended by hundreds of law enforcement officers from across Wisconsin and even from other states.

She was the first officer to be killed in the line of duty in the 96-year history of the Wauwatosa Police Department.