SPOKANE - Hundreds of people attended a memorial service for 11-year-old Christopher Wood as eight more detectives were assigned to the investigation to identify his killer.

Robert Wood, 43, the boy's father, remained in jail after being formally charged yesterday with first-degree theft in an unrelated case involving a former employer.

The boy's mother, Jolynne Wood, who is divorced from Robert Wood, yesterday said she is convinced her former husband is not the killer.

"There's no way any of us think Bob did this to Christopher," she said. "I just can't even imagine that."

The mother has speculated that her son may have been abducted by a stranger.

The father is considered the only "person of interest" in the strangulation of his son, Spokane County sheriff's officers have said.

The memorial service at the boy's school in suburban Newman Lake drew family members, neighbors and classmates.

"I want to just say, `Goodbye, my dear little student,' " said Meg Elyard, his fifth-grade teacher.

The case began when Robert Wood's home was destroyed in a suspicious fire the morning of Feb. 9. Wood said he last saw his son preparing for school about 8:20 a.m. that day.

Eight sheriff's detectives were added yesterday to the five previously assigned to the case. They canvassed the Newman Lake area, asking whether anyone had seen anything strange last week.

"We are looking for everybody that might have seen Chris leave the house, not leave the house, a strange vehicle in the neighborhood," sheriff's spokesman Dave Reagan said.

Detectives have said they don't have enough evidence to recommend a charge against Wood, a roofing contractor and father of six.

In jailhouse interviews this week, Wood denied any involvement in the death of his son.

Detectives are also looking for anyone who saw Wood's white pickup along Dennison-Chattaroy Road, north of Spokane, the morning of Feb. 9.

There was no sign of the boy after the fire was extinguished, and his father speculated he may have fled for fear of being blamed for the blaze.

Investigators have not determined how the fire started but have termed it suspicious.

Last Thursday, the boy's body was found 56 miles away along a rural road near Deer Lake. His backpack was found at another location.

Wood was arrested the same day in the theft case, which involves about $100,000 in money and items reported missing from a former employer. He is being held on a $100,000 cash bond, unusually high for a theft charge.

The judge who set the bail said he considered Wood a flight risk.