The LA Times goes into great detail on the grooming of the 13-year-old and the cop's psychiatric commitment after he cut himself when she tried to end the relationship, if you want to know more. But honestly:
During [his] time in the psychiatric facility [after cutting himself], a local judge barred him from purchasing, possessing or transporting firearms after he voluntarily sought treatment, new records reviewed by The Times show. Officials for courts in the jurisdictions of two known addresses for [the cop] told The Times that they do not have records that indicate that he ever petitioned the court for restoration of his gun rights.
[He] applied to join the Virginia State Police. During the hiring process, he disclosed that he had voluntarily checked himself into the mental health facility in 2016. That disclosure should have prompted further investigation, but didn’t. “Human error” and an incomplete query of databases led to [his] application being approved, a Virginia State Police spokeswoman later acknowledged.
In July 2021, around five years after he was institutionalized and had his gun rights taken from him, [he] entered the Virginia State Police Academy.
On Jan. 21, 2022, [he] graduated from the academy. He resigned after less than a year, and applied for a job as a deputy with the Washington County Sheriff’s Office, listing his own father as a reference. He started that job on Nov. 16, 2022.
On Nov. 25, [he committed the recent murders]
Also, here's how the Times originally got some of messages between the cop and the 13-year-old:
The messages, portions of which were initially shared with The Times by [a] co-host of “It’s Cryptic Out There,” a crime and paranormal podcast