A 62-year-old Kent man pleaded not guilty to second-degree murder for allegedly killing a former girlfriend 21 years ago.

Phan Kim Seng, a retired Renton car salesman, entered the plea Nov. 7 at the King County Courthouse in Seattle. Seng is scheduled to return to court Jan. 7 when a trial date could be set or attorneys could ask for more time to prepare the case. Seng remains in the King County Correctional Facility in Seattle with bail set at $2 million.

Prosecutors claim Seng killed Nguyet “Anna” Nguyen, of Burien, on or about Nov. 9, 1998, because he was unwilling to accept the end of their relationship and so she could not marry her fiancé, according to charging papers filed in King County Superior Court. Prosecutors also claim Seng killed Nguyen so he would not be convicted in a fourth-degree assault case when he reportedly tried to strangle her.

King County Sheriff’s Office detectives arrested Seng the morning of Oct. 25 at his Kent home in the 10000 block of Southeast 220th Street.

Relatives reported Nguyen missing when the 28-year-old, the mother of an 11-year-old daughter, never returned home after telling her mother she was going to visit her fiancé, according to court documents. She has not been seen or heard from since that night. Although her body has never been found, the King County Medical Examiner’s Office issued a death certificate for her in 2015.

Detectives questioned Seng, then 42, shortly after Nguyen’s disappearance, but didn’t arrest him for the killing. On Nov. 11, 1998, Nguyen’s vehicle was located in the parking lot of a Tukwila casino. Seng denied having any involvement in her disappearance. But detectives noted that he provided ever-changing stories regarding his whereabouts during the time in which Nguyen went missing. Detectives learned that the day she was reported missing, Nguyen had plans to fly to Reno with her fiancé to get married.

Earlier this year, Major Crimes Detectives re-examined the case, along with its evidence. During this review, facts were gathered that weren’t previously known to detectives, leading them to Seng in connection with Nguyen’s disappearance and suspected murder, according to the King County Sheriff’s Office.