It was supposed to be his first day at work at Virginia Mason Medical Center in Seattle, so when Louis Chen didn’t show up, a hospital worker went to the 17th floor of his high-rise apartment building and knocked on the door.

Chen, an endocrinologist, answered it nude, holding a box for cover. He was dirty with dried blood, and his right eye was swollen shut.

That morning of Aug. 11, 2011, prosecutors said, his penthouse was a grisly scene — bloodstained letters were scattered around the along with two lifeless bodies and five knives that were thought to be used in their deaths.

Chen, who was found with a cocktail of over-the-counter cold and cough medicines in his system, had been on a murderous rampage, prosecutors said. They said he brutally murdered his partner, 29-year-old Eric Cooper, stabbing him over and over in his face, neck and body. Then, they said, he turned to the couple’s 2-year-old son, Cooper, cutting the toddler’s throat from ear to ear, according to court documents