Man Facing Life in Prison After Admitting He Murdered Seattle Mom-of-3 Who Was Later Found Dismembered

The 38-year-old man accused of killing and dismembering a Seattle-area mom last year pleaded guilty on Monday to her first-degree murder, PEOPLE confirms.

According to investigators, John Robert Charlton, who has been described as a homeless day laborer, strangled Ingrid Lyne, a 40-year-old nurse and divorced mother-of-three, on the morning of April 9, 2016.

Charlton and Lyne met on an online dating site and had been seeing each other for about a month before her slaying, he told police. One of her friends told PEOPLE they had been seeing each other for six to eight weeks.

Lyne was reported missing after, Charlton said, the pair went on a date to a Seattle Mariners game on April 8, 2016. Two days later, police found a head, arm, and leg bagged up in a Seattle recycling bin. Authorities identified the remains as Lyne’s.

A motive for the murder — which occurred in Lyne’s home in Renton, Washington — has never been disclosed and investigators initially suspected Charlton of being a serial killer. However, he has only ever been charged with Lyne’s killing.

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Charlton will be sentenced on Jan. 5. While he faces a possible sentence from a judge of life in prison, prosecutors are expected to recommend a term of 27 years and nine months — the maximum they are allowed under the law.

Charlton also pleaded guilty on Monday to theft of a motor vehicle belonging to Lyney, court officials confirm.

He initially told investigators he had blacked out and could not remember attacking Lyne, according to court documents.

Police recovered a 15-inch pruning saw from Lyne’s bathroom, which they believe Charlton used to carve up her body.

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“Our community was shocked by the senseless murder of Ingrid Lyne,” King County, Washington, Prosecutor Dan Satterberg said in a statement obtained by PEOPLE.

“We have charged the most serious crimes we could under the law, and now that this defendant has pled guilty, we will be recommending the maximum prison sentence,” Satterberg said.

Lyne is survived by her three daughters, who were 12, 10 and 7 at the time of her death.

A call to Charlton’s attorney was not immediately returned on Wednesday.