A Maplewood man’s savage hammer attack on his mother last winter has earned him 20 years in prison.

David Edward Williams Jr. took his mother hostage in her Woodbury house the evening of Jan. 21 and struck her in the head several times before taping her to a chair.

Then he texted his father with her phone, luring him to the house, before threatening both parents with a loaded 12-gauge shotgun, according to the criminal complaint.

“The facts are just horrid,” said Fred Fink, the criminal division chief in the Washington County attorney’s office.

Williams, 23, was sentenced last week in Washington County District Court on a conviction of first-degree premeditated attempted murder. A second charge, second-degree firearm assault with a dangerous weapon, was dismissed.

Judge Mary Hannon gave Williams credit for 305 days served in the county jail, and ordered $13,662 in restitution from his wages at St. Cloud state prison.

Williams, who has a bipolar condition, had stopped taking his medications and was drinking alcohol and taking drugs when the attack occurred, according to the complaint. He was angry at his parents for having medicated him as a child, the complaint said.

As his mother pleaded, “Please don’t hurt me,” Williams closed all the blinds and opened a large black bag that contained a shotgun, baseball bat, knife and hatchet.

After striking his mother with the hammer, he menaced his parents with various weapons and told them he planned to smoke marijuana before killing himself.

He finally allowed his parents to flee. His father drove his mother to Woodwinds Hospital in Woodbury, where doctors determined that she had an open skull fracture and a traumatic brain injury.

Williams surrendered to a law enforcement SWAT team after hours of negotiations. Police recovered the weapons, including several knives, and a journal-type document in which Williams had written after the attack:

“Last day. Decided to show mercy. I didn’t think I could spare them but I guess I can. Good bye. I’m sorry I hit you. I’ve lost my mind.”