King County prosecutors have charged a Los Angeles man with killing a Redmond woman he was dating when she was last seen more than a decade ago.
Mark Frisby, 44, was charged Wednesday with second-degree murder in the death of Lorill Sinclaire, who was 49 when she was reported missing in 2011. Prosecutors asked he be held in California on $3 million bail while they seek his extradition to Washington.
Prosecutors also called Frisby a “flight risk” and argued he was likely to commit a violent offense if released, referencing a prior California conviction for attempted murder and assault, according to court documents.
Law enforcement officials initially reported Sinclaire’s disappearance didn’t involve foul play. The case went cold before officials reopened the investigation last year.
Sinclaire’s mother told police she’d last heard from her daughter Nov. 9, 2011, after Sinclaire went to visit Frisby, her boyfriend at the time, according to probable cause documents.
Frisby’s and Sinclaire’s relationship was described as volatile, according to police records. Sinclaire’s family expressed concerns over Frisby’s behavior and his unfounded accusations against Sinclaire, according to court documents.
Police in Bellevue, where Frisby was living at the time, conducted two welfare checks for Sinclaire – one of the checks coming after Sinclaire’s ex-husband entered Sinclaire’s empty apartment through a broken window and found the bathroom floor was unusually cleaner than the rest of the apartment, according to police documents.
He also noticed other unusual things, records say, including the tub being full of at least a “roll’s worth of paper towels.”
Sinclaire’s ex-husband spoke with Bellevue police, but he claimed they sounded “disinterested in his story,” according to court documents.
Police told him they had already been at the residence and found nothing “suspicious,” records say.
Sinclaire’s family filed an official missing person’s report and told police they believed Frisby was involved. Police said they had no indication of foul play as they investigated.
Bellevue and Redmond officers returned to Frisby’s apartment the day after Sinclaire’s family filed the report and found Frisby in an ambulance van where he said he was living after being evicted.
A Redmond officer noted Frisby’s extensive stock of cleaning supplies and how the apartment had been exhaustively cleaned, police documents say.
Frisby told police he was hoping to get a cleaning deposit returned – a claim the landlord disputed. He told police he thought Sinclaire was “hiding,” according to police documents.
An officer who interviewed Frisby noted his story was “inconsistent” and that he went on “tangents,” according to police documents.
A physician noted Frisby was suffering from paranoid delusions after he visited the doctor over poisoning concerns he blamed on Sinclaire. A social worker said he might have been suffering from paranoid schizophrenia, as he believed he was being poisoned and assaulted.
Phone records showed there had been several back-and-forth calls between Frisby and Sinclaire a day before her mother initially called police for a welfare check, documents show. Her phone was disabled that day, and Frisby’s phone records showed he never tried to contact Sinclaire afterward, which was extremely unusual given their daily call log history, according to court documents.
Frisby’s phone was then disabled, and it was later determined he had showed up unannounced at the Portland home of a friend, who told police Frisby seemed “out of it” and unconcerned about his girlfriend’s disappearance, documents say. Sinclaire’s phone was never found.
Sinclaire’s abandoned vehicle was later found in a Bellevue church parking lot. Authorities found her journal, where she had expressed concerns over Frisby’s escalating behavior and mental state. She wrote that it was like he “flipped a switch” and became accusatory, making Sinclaire concerned for her safety, according to court documents.
Frisby moved to Las Vegas the month after Sinclaire’s disappearance, and Las Vegas police notified Redmond police of his whereabouts. Authorities found a receipt showing he’d pawned a knife, according to probable cause documents. The knife was examined in 2012, but nothing linking him to Sinclaire’s disappearance was found.
Frisby downplayed his relationship to Sinclaire during interviews with detectives and continued denying knowing her whereabouts.
The knife was resubmitted for analysis in 2022 after advancements in forensics technology, which yielded a DNA match for both Frisby and Sinclaire.
“We never forgot Lorill and are grateful to have identified the person responsible for her tragic murder,” Redmond Police Chief Darrell Lowe said in a statement. “We hope this arrest can provide her family some closure.”
Detectives concluded Frisby likely killed Sinclaire with the knife, given the DNA match and the exhaustive cleaning supplies Frisby purchased. Sinclaire’s body has not been found.
Police are asking anyone with information to call detectives at (425) 556-2500.
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