You don't have google? Second hit is a review board finding against him:
Dude is not a physician. Not an MD or DO. Hes a DC ( "doctor" of chiropractic) And he gave up his license to practice chiropractic in Minnesota.
Sounds shady. Just your basic grifter with some weak credentials who gets people to pay him for holistic and diet advice. Y'know, an expert who lacks accountability to science or any actual legitimate licensing agency.
He voluntarily gave up his license, but it's most definitely a disciplinary hearing, where he pretty much stipulates he has been practicing outside of his licenses scope.
Frankly, my personal opinion is "MEGA shady" because his client/victim list is clearly a bunch of very vulnerable, messed up people.
He is not just some fast talking chiropractor who drifted into handing out holistic/diet advice.
He's a weasel. Note that 3 of the 12 patients are psych patients, and that he slept with patient #12, a chronic pain patient, and was bonking her for 3 months till it all crashed badly. He basically acts as kind of a father figure/guru to her, wins her idealized admiration, then makes a show of "ending" the doctor-client relationship, so that he can nail her and remain "professional". "Relationship" predictably ends in a few months.
Funny, I expected at least one of these to end with sex.
I don't even know him or any of his victims, and I want to kick his teeth in. Smart-ish guy with predatory instincts, your basic scumbag. Definitely the type to start a cult if he had a little more ambition and charisma.
All of the above is my personal opinion based on life experience and intuitive read. I am not a licensed psychiatrist or psychologist. I am pretty confident in my opinion here though.
His nonprofit seems to be a fraud. It's presented as a charity that he raises funds for... and yet money raised actually goes to a school that he seems to run - and elsewhere he shows off his titles as if they're impressive credentials. Its location and even existence in any real sense are unclear.
I have, unfortunately, personal experience with this guy and I can tell you he's all smoke and mirrors, and is a narcissistic sociopath. Hopefully your sister has figured it out by now! His "retiring" his Chiro license was to avoid a sexual harassment hearing, which involved multiple claimints. It was on the Internet but looks like it was removed. He preys on young women, and his patient base makes it pretty convenient. I personally think he is NOT an MD in Europe or anywhere, but try and verify that--it's impossible to track down and he knows that. Steer clear. He's dangerous.