Michael Chadd Boysen paid for his flight from Fairwood with cash and jewelry he stole from his murdered grandparents, including his grandfather’s wedding ring he pawned in Kent, according to King County prosecutors.

Prosecutors and King County Sheriff’s detectives spelled out their case against the 26-year-old Boysen in documents filed Thursday, charging Boysen with aggravated first-degree murder in the deaths March 9 of his grandparents, Robert and Norma Taylor.

Boysen was transferred by the state Department of Corrections early Thursday afternoon to the King County Jail in Seattle, where he is being held without bail.

Boysen is accused of murdering his grandparents just hours after they picked him up at the state prison in Monroe. He was arrested on March 12 in Lincoln City, Ore., after a 10-hour standoff with police.

If he’s convicted, Boysen faces two sentences, life in prison or death, according to the prosecutor’s office.

The charging documents offer many already-released details of how Robert, 82, and Norma, 80, welcomed home their grandson from prison on Friday, March 8, including hosting a small party for the family. The party ended at about 9:30 p.m.

Initially, investigators didn’t release or didn’t know a motive for the slayings.

On March 10 a detective interviewed two inmates at the state prison in Monroe, who recounted how Boysen had spoke of his anger toward his grandparents and his desire to kill them. He said he planned to steal their  cash and car.

Boysen’s mother, Melanie Taylor, the Taylors’ daughter, checked on her son and grandparents the early evening of March 9, after another relative wasn’t able to contact the Taylors at noon as planned.

Using a key, Melanie Taylor went inside the house on 145th Avenue Southeast in Fairwood. She didn’t immediately see her adopted son or parents. She waited for a few minutes, then looked around. She found her parents dead in the closet of a spare bedroom, where her son was supposed to sleep. She called 911 at 6:15 p.m.

Boysen was gone, as was her parents’ red 2001 Chrysler 300.

Detectives with the King County Sheriff’s Office couldn’t find any signs the house was forcibly entered. There weren’t signs of a struggle.

The county medical examiner, in ruling the Taylors’ deaths homicides, indicated the couple had been strangled to death. Part of a bloody shoelace was found on Norma Taylor’s neck.

A jewelry armoire was found intact in the master bedroom and a second also was locked and apparently untouched.

A ledger showed regular deposits of cash into two now-torn and empty envelopes. The last entry was March 8 for a total of $5,200 in cash saved during almost seven years. Norma Taylor was known to save cash at home.

Boysen paid cash for a 2002 Ford Taurus in Salem, Ore., not far from where his grandparents’ Chrysler was found in a Walmart parking lot, according to charging documents.

Robert Taylor’s American Express Card was used at 7:07 a.m. March 9 at the Walmart in Covington to buy $600 worth of music CDs, an iPad tablet computer and protective case and a 25-inch suitcase. About 90 minutes later, an $800 charge was made against Taylor’s Visa card at a Fred Meyer for a pre-paid cell phone and an HP laptop computer.

On March 14, detectives searched the trunk of the Taurus. Inside were Robert Taylor’s wallet, the HP computer, a tool chest full of jewelry, a Lane cedar box containing men’s and women’s wrist watches, a Winchester rifle and several cans of kerosene and propane bottles.

On March 15, detectives learned from Melanie Taylor that a jewelry armoire had been opened, emptied of expensive jewelry and locked again. The couple’s sterling silver silverware was gone.

A sheriff’s detective learned that on March 9 Boysen had sold bags of jewelry, silverware and coins to AC Coins in Kent; he had told a clerk he purchased items at an estate sale in Lebanon, Ore., according to charging documents. The documents note that Boysen’s father lives in Lebanon.

Among the jewelry recovered was Robert Taylor’s wedding ring, inscribed with the date he and Norma wed nearly 60 years earlier, March 5, 1954.

In an interview released through the Sheriff’s Office, Melanie Taylor recounted how her parents loved Chadd “more than life itself.”