King County Deputy Prosecutor Scott O'Toole said he expects to file four counts of aggravated first-degree murder on Monday against Conner Michael Schierman, 24, who was held on $4 million bail following his first court appearance Thursday. O'Toole said no decision had been made about whether to seek the death penalty.

"He admits to setting the fire. He admits to leaving the victims' house covered in blood," O'Toole said.

Investigators had not determined a motive for the killings, and a motive may never be known, given Schierman's claim to have blacked out and damage from the fire, which gutted the two-story house, O'Toole said.

"The damage to the victims is pretty horrendous and pretty complete," he said.

The Seattle Times and Seattle Post-Intelligencer, each citing an unnamed law-enforcement source, reported Friday that investigators believe Schierman showered to wash off the blood, stole some clean clothing, then set the house on fire with gasoline to try to cover up the killings.

The fire at the family's home in Kirkland, across Lake Washington from Seattle, was reported shortly before noon on Monday. Two neighbors reported seeing a man matching Schierman's description nearby at the time, O'Toole said.

After the fire was out investigators discovered the bodies of Olga Milkin, 28; her sons Justin, 5, and Andrew, 3; and her sister, Lyubov Botvina, 24, who lived at the house..

The King County medical examiner's office found three of the four had been stabbed repeatedly in the neck, head and chest, and the throat of the youngest was slit.

At the time of his arrest Wednesday for investigation of arson and homicide, Schierman appeared to have defensive wounds to his arms and face, O'Toole said.

Olga's husband, National Guard Sgt. Leonid Milkin, assigned to the 415th Military Intelligence Battalion in Baghdad, returned Thursday on emergency leave. Still wearing military fatigues, he glanced briefly at a memorial before entering the home with investigators but spent most of the day with family.

"You can only imagine what he could be going through - to come back and find his home burned and his beloved family dead, gone," said Maj. Philip Osterli, a Guard spokesman.

The six-foot, 215-pound Schierman moved in across the street from the Milkins earlier this month. He was brought into a King County jail courtroom in a white jumpsuit, ankles shackled and hands cuffed behind his back. A judge found probable cause to detain him and set bail as some of Schierman's relatives watched.

Schierman's lawyer, Jim Conroy, would not discuss the case but said his client has no criminal history, "no involvement in the criminal justice system whatsoever."

Schierman and his younger sister both had "serious emotional difficulties relating to their father's alcoholism and the divorce," his mother wrote in court papers filed with the divorce in 1999, the Post-Intelligencer reported.

Schierman, then 17, "was so affected by these events that he became suicidal" and was "being treated for depression and is attending an alternative high school," his mother wrote.

School officials could not confirm on Thursday whether he completed high school. His picture appears in the senior class in the 2000 annual of Newport High School in Bellevue, but on another page he is mentioned as a junior, the Post-Intelligencer found.

Carl McGavran, manager of the Sierra Fish & Pet store in Bellevue where Schierman worked off and on for about six years, told the Post-Intelligencer and The Times he knew Schierman was an alcoholic but had never seen him violent.

McGavran told The Times he fired Schierman a couple of times for failing to come to work - "he'd say he blacked out" then rehired him.

Schierman has been working for the past year and a half doing maintenance for Carillon Properties, an upscale collection of offices, shops, a hotel and a marina on Lake Washington in Kirkland.

"He's always been a good worker," said Carillon general manager Barbara Leland. "He had no problems, no warning signals, nothing. Everybody liked him."

Toward the end of last month, when they met to shoot pool, "he seemed in really good shape," McGavran told the Post-Intelligencer. "He talked about moving into some new place. He said his job was going well, that he was still sober. He seemed totally upbeat."

But on the Web site MySpace.com, Schierman reveals past struggles with alcohol and drugs.

In a blog entry three weeks ago, he describes himself as a product of "divorce and abuse," writing:

"I was a liar, a con man... I had a different face and set of emotions for each person I knew. Fueled by drugs and alcohol, I viewed the world with jaded, veiled eyes...I spent my trust on lies and deceit. deny, deny, deny.... I was a mess..."

But, he added, he had come clean recently, writing:

"With time, patience, work and fortitude, these wounds are healing..."

Residents of a house for recovering alcohol and drug abusers told reporters that Schierman had lived there until recently.