Two and a half years after declaring his “martial times” over and done with, Mirko Cro Cop is back in a major MMA promotion.

But in a way, he never really left this sport, despite a two-year suspension for violating the UFC’s anti-doping policy under USADA, which is where things get complicated.

Monday, Bellator announced Cro Cop will make his debut for the promotion in a heavyweight rematch with fellow former UFC fighter Roy Nelson at Bellator 200 in London on May 25.

But Cro Cop has been in a sort of MMA exile since November 2015, when he abruptly retired just before news broke that he’d admitted to using human growth hormone prior to a scheduled UFC bout against Anthony Hamilton. USADA handed down a two-year suspension for that offense. It made Cro Cop the first fighter to run afoul of the UFC’s new anti-doping program, and eventually led to his release from the UFC.

Except, once he was cut from his contract, Cro Cop, 43, decided maybe his martial times weren’t over after all. He fought for Japan’s Rizin FF promotion less than a year later, winning an open-weight grand prix to close out 2016. He most recently fought for Rizin FF a little more than two months ago and beat Tsuyoshi Kohsaka via first-round TKO on New Year’s Eve.

In that sense, Cro Cop never sat out the required two years to serve his suspension. So is he eligible to fight for Bellator, which doesn’t have a policy with USADA, but typically does adhere to state athletic commission standards, even for overseas events?

The answer to that question still seems hazy. According to Mike Mazzulli, president of both the Association of Boxing Commissions and the Mohegan Tribe Department of Athletic Regulation, which will regulate Bellator’s event in London, he reached out to Cro Cop when news of the fight was announced, but still considers him in the process of being licensed, and therefore subject to immediate drug tests.

“Here at Mohegan, the minute a medical is provided to me, they’re considered to be in the process of being licensed, so I have the authority to test them,” Mazzulli told MMAjunkie. “I’ve already reached out to (Cro Cop) and informed him that I want a test. I’m researching it right now.”

Generally, athletic commissions in the U.S. follow USADA suspensions. But it seems unclear whether a fighter can actually serve a suspension if he simply takes his talents to an unregulated promotion in Japan, then returns once enough time has elapsed.

If Cro Cop can fight for Bellator in London, could he also fight in, say, California? That’s “tricky,” and would depend on the circumstances at hand, according to California State Athletic Commission executive director Andy Foster.

“Our jurisdiction is only in California and by the extension in the U.S. with the ABC,” Foster told MMAjunkie via text, in response to a question about Cro Cop’s eligibility.

According to Mazzulli, as long as Cro Cop can pass his drug tests leading up the fight, his commission is likely to view the suspension as a thing of the past, even if Cro Cop never actually sat out from MMA competition for two consecutive years to serve it.

“The last thing I want to do is adversely affect a guy’s career,” Mazzulli said. “There’s only so many years they have the ability to earn. In my opinion, and in the Mohegan Tribe’s opinion, 2015 was three years ago, so it’s time to allow him to fight and make a living.”

Still, it does bring up some complex questions about MMA’s ability to deal with doping. If a fighter can compete elsewhere, fighting and getting paid while technically on suspension in other jurisdictions, is he really being punished? Can he even be said to have been suspended?

It’s also an issue that Bellator seems likely to confront with some frequency. Bellator officials would only say that the Mohegan Tribe commission had “approved the (Cro Cop-Nelson) matchup and will be overseeing the London event from a regulatory perspective.” But already its roster is populated with fighters like Chael Sonnen and Frank Mir, both of whom exited the UFC under the cloud of doping violations.

Cro Cop adds to that list, as would Wanderlei Silva, whom Bellator plans to pit against Quinton Jackson in an upcoming event in Brazil.

So far, Bellator has largely gotten a pass on the anti-doping issue from fans and media, without any significant pressure to follow the UFC’s lead in signing on with an independent third-party anti-doping agency for year-round out-of-competition testing.

But if Bellator becomes the consistent next stop for big-name fighters who have drug-tested their way out of the UFC, that could change.

There’s also the question of how it might change fighter attitudes toward anti-doping violations if Cro Cop’s career path starts to seem like a viable or even normal one. A multiple-year suspension from USADA might seem like less of a problem if a fighter can follow it up with a UFC release and then a short, profitable stay in Japan before signing with a major promotion like Bellator.

As for Cro Cop himself, Mazzulli said he plans to test him “out-of-competition, in-competition, and post-competition” in order to ensure he’s clean.

“I’m a guy who believes in fair play,” Mazzulli said.

How that will mesh will Cro Cop’s ongoing martial times remains to be seen.

For more on Bellator 200, check out the MMA Rumors section of the site.