Former Kings center Mike Richards was charged with possession of a controlled substance after an investigation by the Royal Canadian Mounted Police.

The charges, which were levied Tuesday and announced Thursday, followed a two-month investigation by the agency. The probe was sparked by the detention of Richards at a Canadian border crossing on the afternoon of June 17.

The Winnipeg Free Press posted a copy of a document from the RCMP citing the alleged substance as Oxycodone. It was not specified how much Oxycodone was seized.

Richards was detained for several hours at the Emerson border stop, an entry point from North Dakota into the Canadian province of Manitoba. Canadian Border Services Agency officers intercepted the controlled substance at the Emerson port of entry, and the case was turned over to the RCMP, according to a statement released Thursday from the agency in Manitoba.

Richards is scheduled to appear in Emerson Provincial Court on Sept. 10.

Prosecutors in Manitoba could proceed summarily, a course of action for less-serious offenses, or by indictment, reserved for more serious matters.

"This is an offense for which there is a huge [sentencing] range," said University of Manitoba law professor Debra Parkes. "It will all depend on the seriousness. I've seen examples of people getting discharges for possession of Oxycodone. There are some examples of that across Canada, if the person is an addict, if it is a relatively low amount, no record, that kind of thing. It could be a fine, or could possibly be imprisonment.

"Without a record, and assuming if it was a small amount, it would be possible to argue even for a discharge. But we don't know enough about the facts."

Less than two weeks after Richards was detained at the border, the Kings moved to terminate his contract, citing "a material breach."

The Kings declined to comment on the legal developments in Manitoba, citing the ongoing litigation regarding the contract grievance. Richards' agent also declined to comment.

But when the Kings terminated Richards' contract, they said in a statement: "We are not prepared to provide any more detail or to discuss the underlying grounds for the contract termination at this time."

This month, the NHL Players Assn. announced that it would contest Richards' contract termination by the Kings. No date for the hearing has been set. The impartial arbitrator hearing the case will be George Nicolau.

"We are aware of the legal situation relating to Mike Richards," said NHL Deputy Commissioner Bill Daly, via email Thursday. "We will have no comment on the matter unless or until the situation warrants."

Sports law expert Michael McCann of the University of New Hampshire said previously that the threshold for termination was a high one.

"This is a case that the Players Assn. certainly wants to fight because of the precedent it will create," he said Thursday. "It goes to the heart of whether contracts are guaranteed, and the Players Assn. doesn't want to create a precedent where an underperforming player sees his contract terminated because of some circumstance that would otherwise not lead to the contract termination.

"Certainly the arrest suggests that at least there was a significant incident. I think it helps the Kings, but I don't know if it is a game-changer because the Players Assn. can contend that it should be the circumstances at the time the contract was terminated, not subsequent events that took place."

Richards, 30, was part of the Kings' two Stanley Cup championships, in 2012 and 2014. But his production slipped so much this past season that management opted to send him to the team's American Hockey League affiliate in Manchester, N.H., after the All-Star break.

He was traded to the Kings from the Philadelphia Flyers in 2011 and has a well-documented history of concussions. He suffered one early in his Kings' tenure in 2011 and had another during their run to the Western Conference finals in 2013. He said in the summer of 2013 that he had "three officially on the books," according to a blog post/interview with his then-girlfriend.

Before joining the Kings, Richards had surgery on both shoulders after the 2009 season with the Flyers, and news reports at the time of the procedure said he used anti-inflammatory medicine to keep the pain down.

The arrest of Richards came about two months after another former Kings player, Jarret Stoll, was detained in Las Vegas in April and later charged with cocaine possession. Stoll, now with the New York Rangers, eventually pleaded guilty to two reduced misdemeanor charges.

Currently, Kings defenseman Slava Voynov, who pleaded no contest to a misdemeanor domestic violence charge, is completing his sentence at a detention center in Seal Beach.

lisa.dillman@latimes.com

Twitter: @reallisa