On the day he was to be sentenced to nearly three years in prison, 20-year-old Devon Derrick Parker instead made his way to a north Minneapolis home and knocked on the back door.

Appearing frantic and paranoid, he told homeowner Thomas K. Sonnenberg that someone was chasing him. Moments later, the 69-year-old retired technician, who had let Parker in intending to help him, was dead, shot with his own gun, according to second-degree-murder charges filed Monday against Parker. Authorities still don’t know why Parker allegedly attacked Sonnenberg around noon Friday, or why he even went to Sonnenberg’s house in the 3700 block of Aldrich Avenue N. But court documents show that over the past few months, Parker had been acting strangely in several incidents with his family and police.

In September, police say, he nearly jumped from his girlfriend’s moving car. He was drunk, and when two officers showed up to take him to a detox center, he kicked and punched at them before they could get him under control.

In December, Parker showed up at his mother’s house on Russell Avenue N. smelling of alcohol and told her he was high on “Mollys,” a form of ecstasy, police say. He punched her when she tried to lead him to the door, then threatened to shoot her and others after they pushed him out of the house. When an officer arrived, Parker said he had been shot and that he was running from people; then he broke down, began to cry and asked the officer for a hug, police say. He also admitted that no one had shot him.

Parker, already on probation from two even earlier incidents when those events occurred, was due in Hennepin County District Court on Friday for sentencing in the September assault on the police officers. He would have faced 33 months in prison, according to court spokesman Chuck Laszewski.

A dramatic few minutes

According to the charges, Sonnenberg called 911 at 11:46 a.m. Friday after Parker came to his house claiming that someone with a bat was chasing him. He let Parker in, then locked the door behind him before placing the call.

Four minutes later, police officer Eric Lukes arrived and knocked on the front door but got no answer. He looked through a window and saw a body, later determined to be that of Sonnenberg, slumped over a kitchen chair. He kicked and beat at the rear door until Sonnenberg’s wife, Elaine, called out, saying she could not unlock it.

The officer then saw Parker come up behind her and place his hands on her shoulders, the charges say. Pointing his gun at Parker from outside the house, Lukes ordered Parker to lie down. Parker complied, and that gave Elaine Sonnenberg enough time to unlock the door for Lukes, who arrested Parker.

Thomas Sonnenberg, who had been shot once in the head, was wearing an empty holster on his right hip.

Elaine Sonnenberg told police that she was in the dining room when Parker had come to their door pleading for help and appeared “frantic, paranoid and in some sort of distress.” She heard him ask her husband for a gun, knife, hat and gloves. She then heard one gunshot.

Parker then came out of the kitchen brandishing her husband’s Smith and Wesson revolver, she told police. He ordered her to the floor, then said police were coming and told her to lock them both in an upstairs bedroom.

They went upstairs but came back down when they heard noises and found Lukes at the door.

Parker’s criminal history includes a 2011 conviction for third-degree assault. On July 9, 2011, at nearly 3 a.m., he was standing outside 10 S. 5th St. in downtown Minneapolis when he tripped a man who had just had his cellphone stolen, then jumped on the man and punched him in the face, breaking bones near the man’s eyes.

He was also convicted in 2012 on a charge of crime against transit operation when he boarded a bus without paying. When the bus driver confronted him, Parker punched him, breaking the driver’s eyeglasses, and got off the bus. He then pulled out a gun and shot once, hitting the bus.

Past sentences

Parker did time — 36 days and 180 days — for those 2011 and 2012 convictions, respectively. The sentences are fairly typical of what any defendant would see for such crimes, Hennepin County Attorney Mike Freeman said Monday.

The most recent string of charges, starting with the September assault on two police officers, would have landed him in prison, Freeman said. “My guess is he would have gotten some real time,” he said.

On Monday, at Parker’s listed address, a house not far from where the shooting occurred, a woman who identified herself as his mother declined to comment.

At Sonnenberg’s home, his two grown daughters continued to clean it out. They said their mother will never return to it.

Rachel Baufield and Raina Baldwin said it doesn’t matter whether Parker was high, drunk, mentally ill or even being pursued when he allegedly killed their father.

“If he was, I don’t care,” Baldwin said. “It should not affect judgment on him. Even if he was crazy, if you’re that crazy, you are responsible for getting help before you do anything, even assault.”

Baufield said her mother saw Parker being chased when he arrived at their house. “My dad wouldn’t have let him in the house otherwise,” she said.

The sisters said their father probably lost control of the gun in his holster when he turned his back to call 911 for Parker.

“If my dad thought something was fishy, he wouldn’t have turned his back at all,” Baldwin said. “Living in this neighborhood, he is very vigilant all the time.”

Baufield said she’s concerned, given that her father was killed by his own gun, that his death could be politicized.

“We would be very angry if this got used for the gun control lobby,” she said. “If my dad didn’t let down his guard, this would not have happened. He totally thought he was doing him a favor.”

Baufield said their mother is “holding on.”

“She’s putting up a brave front,” Baldwin said. “She’s not letting it sink in yet because she knows that when she does it’s … it’s a bomb that’s ticking.”