In the photo above: Cousins Joda Cain (r) and Micus Ward (l). This photo was obtained by KGW from Cain's personal Instagram account and the suspects' identities were verified by his friends and classmates.

PORTLAND A 17-year-old is accused of killing his great-grandmother in her Cedar Mill home Saturday with the help of a cousin and then fleeing in the victim's stolen Lexus, police said.

Jacqueline Bell, 71, died of blunt force trauma, according to investigators.

Bell's grandson, Joda Cain, had been living with her.Cain and his cousin Micus Ward, 19, of Kansas City, Mo. were arrested after a high-speed chase on Interstate 84 in Eastern Oregon Saturday.

Police released details of the murder investigation Monday, after they were able to complete an autopsy and analyze evidence in the home and the car. Neither suspect was charged; both were being held on a probable cause warrant.

A Washington County grand jury will convene next Monday to hear evidence in the murder case against Cain. If he is indicted on a Measure 11 crime, he will be charged as an adult.

A friend who attended Sunset High School with Cain told KGW that his great-grandmother had allowed him to move in a year earlier.

The Friday evening before Bell's body was found, the friend said several people were at her house smoking marijuana and drinking, and that Cain had introduced Ward as a cousin.

Cain was reportedly asked whether Bell would be upset by the noise they were making and he responded, Don't worry, I'll hit her. I'll knock her out.

The friend added that Bell was planning an extended trip out of town and that there would be a big party at the house Saturday night.

High speed chase on I-84

A commercial driver first tipped off police after spotting a speeding Lexus passing cars recklessly on I-84 Saturday morning. A trooper quickly spotted the Lexus, which belonged to Bell, and tried to pull the driver over.

The Lexus accelerated to speeds reaching 135 mph, said Sgt. Bob Ray with the Washington County Sheriff's Office. The trooper performed a tactical vehicle intervention, causing the Lexus to spin out. The trooper was able to pin the driver's door closed with the front of his patrol car.

Cain and Ward were detained. Then, deputies tracked the Lexus to Bell's home in Cedar Mill where she was found dead, according to Ray.

Investigators said they don't yet have a motive in the killing. They believe Cain and Ward planned to drive the stolen Lexus to Kansas City, where they both used to live.

Victim was a well-known Portland philanthropist

Bell (pictured below in a photo with Cain circa 2010) was well-known in Portland as a generous donor and volunteer at local nonprofit agencies.

Neighbors and former co-workers said they were shocked by her death.

More: Homicide victim a well-known philanthropist

Read or Share this story: http://www.kgw.com/story/news/2014/07/25/12570218/