A Seattle doctor who killed his partner and their toddler son five years ago was sentenced Friday to 49 years in prison.

King County Superior Court Judge Bill Bowman sentenced 43-year-old Dr. Louis Chen as recommended by prosecutors.

In court, Chen said there was little he could say that could make things better.

"The tear I caused in our universe is profound," he said.

Chen pleaded guilty in February to murder for fatally stabbing 29-year-old Eric Cooper and 2-year-old Cooper Chen, whose bodies were found in 2011 inside the couple's Seattle penthouse.

Eric Cooper was stabbed more than 177 times and Cooper Chen's throat was slashed from ear to ear, prosecutors said.

The sentencing followed a week of testimony from psychiatric experts about Louis Chen's state of mind at the time. Prosecutors said he was motivated by rage over the couple's impending breakup.

Defense lawyers said Chen's ability to know right from wrong was diminished by mental illness, self-medicating and a cough-syrup induced psychosis. They said Chen was considered kind by colleagues and had a history of hard work until he began to deteriorate mentally, The Seattle Times reported.

State mental health workers found Chen competent to stand trial.

Chen, an immigrant from Taiwan, was attending the University of Chicago Pritzker School of Medicine when he met Cooper who was then a high-school senior, friends and relatives of the couple have said.

Detectives found medications, prescriptions and notes written by Chen in their home, which they say provided evidence of a possible dual motive: that Chen feared Cooper would report his prescription-drug abuse and abuse of his prescribing powers as a doctor, or use that information against Chen in a future child-custody dispute.

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