While Richard Lee Christianson and Michael Trinity were painting window screen frames at their home in north Minneapolis on Tuesday, police say Dontaro Riddley and two juveniles were planning a violent armed robbery.

That night, Christianson, 35, and Trinity, 43, were robbed, forced to their knees and shot execution-style in the head.

Police believe Riddley, 19, was the shooter; the other suspects are a 15-year-old boy and his 17-year-old girlfriend.

City and police officials called the slayings cold-blooded and despicable, saying the victims were targeted at random as they walked the four blocks home from Waldo's Bar, a neighborhood hangout, about 11 p.m.

Charges are expected to be filed against the suspects today.

On Thursday, stunned friends and family members gathered near the house Christianson and Trinity shared with Christianson's cousin Mike Wiener.

"Who does that to people?" Christianson's brother David Wiener asked, referring to the execution-style nature of the killings.

Mike Wiener said he heard news reports about the shooting Wednesday morning and called police when he saw that Christianson and Trinity weren't home.

"I was shocked," he said. "Rich and I grew up together. He was like my brother."

'It hurts me,' grandma says

Josephine Riddley said she hadn't seen her grandson, Dontaro, for about a month.

"You never know what your children will do," she said. "I wouldn't think he would do something like that. I am awfully sorry for them," she said of the victims' families. "It is hard to believe he could do something like that. It hurts me."

Quindra Riddley, 18, said her brother had been staying with an aunt in the 4800 block of Aldrich Av. N. -- three blocks from Waldo's and just over a block from the victims' home.

She said her brother had dropped out of high school but had returned to an alternative school and had been trying to get a job as a telemarketer.

"I never thought he would be involved in something like that," she said.

The victims didn't know the suspects and weren't involved in any illegal activity, police Capt. Mike Martin has said. The victims willingly gave up their wallets, police said. Police found a gun that they are testing to determine if it was used to kill the men, Martin said.

There might well have been a third dead man Tuesday night near Waldo's, but, according to police, the suspects' gun jammed during another robbery about an hour earlier.

Armed robberies