A boyfriend said he 'thought' he had to kill six members of his girlfriend's family during a Christmas Eve dinner as he took to the stand in a bid to avoid the death penalty. Joseph McEnroe, 36, from Carnation, Washington, was convicted of slaying four adults and two children - aged three and five - in 2007 by a jury last week. The same 12 people that found him guilty of the murders are now determining whether he will be executed or sentenced to life in prison without parole. Scroll down for video . Joseph McEnroe, 36, from Carnation, Washington, (pictured in court on Thursday) who murdered six members of his girlfriend's family on Christmas Eve, 2007, is testifying in the penalty phase of his trial in a bid to avoid the death penalty . In an attempt to spare his life, McEnroe told the court on Thursday he 'thought' he had to kill Wayne Anderson, 60, and Judy Anderson, 61; their son and daughter-in-law Scott and Erica Anderson, both 32; and the younger couple’s children Olivia, 5, and Nathan, 3. The court heard that McEnroe and his girlfriend Michele Anderson gunned them down and then hid their bodies in a shed behind the house. 'I know that’s not a good excuse' he said. 'I’m not trying to excuse myself. I’m trying to explain my actions. 'There is no question I did these awful things. I thought I had to.' During his testimony, according to KIRO-TV, he claimed he was abused as a child at the hands of his unstable mother and her boyfriends. Wayne and Judy Anderson (pictured) were the first to be killed by Joseph McEnroe on Christmas Eve 2007. McEnroe had been living with his girlfriend in a mobile home in the backyard at the time . Erica and Scott Anderson (pictured) and their children were also shot and killed during the holiday gathering . According to The Seattle Times, he was constantly interrupted by the prosecutor or court reporter, asking him to speak up or slow down. At one point he started giggling and had to apologize to the court room for his 'terrible' speech impediment. He added: 'I did not do this because I wanted to. I was trying to protect Michele. I was completely wrong. Anderson had been living in a mobile home with McEnroe on her parents' property and prosecutors said the couple was upset Michele's parents did not pay their rent. The defense called Dr Donald Dutton, a professor of psychology at the University of British Columbia, who said McEnroe was a victim of 'folie à deux.' Michele Anderson, McEnroe's girlfriend, is set to stand trial for the brutal killings later this year. Court hearings have been delayed because of concerns over her mental capacity . Because he had shared a home with Anderson, Dutton explained, McEnroe had become to believe her claims she had been sadistically abused by her father. Anderson will face trial for the killings later this year, but court hearings have been delayed over questions regarding her mental competency and whether she is fit to stand trial. If the jury decides on the death penalty, McEnroe would be the first person sentenced to death in King County since 2010. There is currently a moratorium on executions while Washington Governor Jay Inslee is in office.
Joseph McEnroe, 36, was found guilty of six murders last week .
Slayed four adults and two children in Carnation, Washington, in 2007 .
Was staying behind the house with girlfriend Michele Anderson at the time .
Jury is deciding whether he is jailed for life or is condemned to death .
Mumbled and giggled as he testified in a bid to avoid execution .