A Washington state man who authorities say killed a woman after luring her into the woods in a Seattle suburb with the promise of digging up buried gold is now charged with the murders of three other victims.

Investigators suspect that Richard W. Bradley Jr., 40, committed the alleged serial killings between 2019 and 2021 in the area of Auburn, a King County city located about 30 miles south of downtown Seattle. Bradley was first arrested in May 2021 and charged in connection to the death of Brandi Blake, who was 44 when her body was found in Game Farm Park in Auburn, according to court documents.

In the last two weeks, prosecutors have filed three additional murder charges against Bradley.

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Prosecutors: Bradley lures victims with promises of buried gold

In all of the deaths, prosecutors accuse Bradley of using the same scheme in which he lured his victims to wooded areas under the ruse of helping him exhume gold he had buried from previous robberies. Once he had them alone and isolated, Bradley is accused of killing them and burying their bodies deep in the parks.

Witnesses interviewed by investigators admitted to having heard about the scheme and even reported seeing Bradley driving the victims' vehicles after their disappearances, according to a probable cause affidavit signed by a King County Sheriff's detective.

Bradley has entered plea of not guilty and is being held in jail without bail as he awaits the resolution of his case, court records show.

First murder suspected in 2019

Investigators suspect that the first murder occurred in July 2019 after the disappearance of Emilio Raul Maturin, who was 36 when his girlfriend reported him missing, charging documents say.

The woman had told Auburn police that prior to Maturin's disappearance, she had overheard him talking with Bradley on July 18 about a "sketchy" plan to unearth some buried gold in Auburn. Though she said Maturin was skeptical, the man eventually agreed to go with Bradley in his recently purchased BMW, according to the charging documents.

Maturin's girlfriend told police that she tracked Maturin's cell phone to Game Farm Park before she "got scared and left," documents say.

That same day, Auburn police found an unregistered BMW parked near a large field at the park. Police attempted to stop the driver when he returned to the car, but he instead took off, prompting a pursuit that ended with Bradley arrested and charged with eluding police, according to charging documents.

Maturin's girlfriend filed the missing persons report two weeks later on Aug. 2.

Maturin's ribs found at park near Blake's grave: Court documents

But it wasn't for another two years until signs of Maturin's remains were found at the sprawling park.

King County Sheriff's detectives investigating the disappearance of Blake found her body May 26, 2021 at Game Farm near a freshly-dug empty hole and a pick and shovel. Also found nearby were three rib bones on top of the ground that were not Blake's, and which had been there long enough to be "bare of flesh," a detective wrote in the probable cause affidavit.

A medical examiner later determined that they were human bones, while DNA testing concluded that the ribs had a high probability of belonging to Maturin.

Two others – father and son Michael Goeman, 59, and Vance Lakey, 31 – were lured in March 2021 to a different wooded area in Auburn, prosecutors said in court documents. Two small shovels were found next to the victims' decaying bodies, and witnesses told investigators that Bradley was seen driving their car and motorcycle when they first vanished.

Bradley became a person of interest after their bodies were found on an unmaintained road not far from the park, the Associated Press reported. He was charged that May with second-degree arson after prosecutors said he offered a man $1,000 to set fire to the father and son’s impounded SUV.

On Thursday, prosecutors added two counts of second-degree murder.

All of the victims had large sums of money either on them or in their names when they were killed, according to the Associated Press. Goeman received a large inheritance just before he and his son were killed, while Maturin was carrying $15,000 in cash on him when he left with Bradley in 2019.

When Blake went missing in early May 2021, she had just won $20,000 at a casino.

Bradley faces life in prison if convicted on the charges.

Contributing: The Associated Press