MINNEAPOLIS (WCCO) – The man accused of beating a northern Minnesota woman and her son to death with a pipe wrench earlier this week told authorities that he suffers from mental illness and that that his victims were part of a family who let him live with them.

“I’m sorry. I’m sorry I did it,” William Hillman told deputies after being arrested, according to a criminal complaint filed in Otter Tail County. The 21-year-old added that he had no memory of the early Tuesday morning assault, only a realization that he had done “a bad thing.”

READ MORE: Minneapolis Police Investigating Saturday Afternoon Shooting In South Minneapolis

Hillman, of Frazee, is charged with two counts of second-degree murder in the deaths of 42-year-old Denise McFadzen and 21-year-old Dalton McFadzen.

Deputies found their bodies shortly after 5 a.m. Tuesday at their Perham trailer home after a relative called 911, reporting that Hillman had attacked them and tried to leave in a car.

Both the deceased suffered severe head trauma, the criminal complaint states.

Minutes after authorities arrived at the scene, Hillman called 911 and turned himself in, telling dispatchers he was at a neighbor’s home. Deputies arrested him without incident, noting he was covered in blood.

READ MORE: Woman Injured In South Minneapolis Shooting, Police Say

In an interview with investigators, Hillman said he suffers from schizophrenia and that he doesn’t remember the attack, only the moments immediately before and after, the criminal complaint states.

He added that he had assaulted his own mother in the past and had been committed to a treatment center in St. Peter. He told investigators that he stopped taking his medication about five months ago, when he went to live with his father in California.

When his father went to jail, Hillman returned to Minnesota and lived, for a time, with a friend in Detroit Lakes, he told authorities. About a month-and-a-half ago, he moved in with the Mcfadzens, the complaint states.

When asked if the family had ever threatened him, Hillman said they had not. He only described them as “weird,” adding that he planned to tell their relatives he was sorry for killing the.

MORE NEWS: Minnesota Weather: Saturday To Hit 87 Degrees In Metro, Temperatures Back Up To 90+ On Sunday

If convicted of the murder charges, Hillman faces up to 40 years in prison on each count.