The Russian man who flew into LAX without a passport or boarding pass last year reportedly had his documents seized in Copenhagen, but he still was able to board a flight to the U.S. after being told to remain in the European airport, investigators believe.

Sergey Ochigava told investigators he didn’t know how he’d ended up in Los Angeles without the required documents, and initially, neither did the airline or government officials.

Now, however, Department of Justice filings are shedding light on Ochigava’s journey, including the actions that led him to L.A., according to a report by Seamus Hughes’ Court Watch and 404 Media.

After “tailgating an unsuspecting passenger through a security turnstile” in Copenhagen, he was nabbed by Danish border police, who determined he’d overstayed on his Israeli passport and did not have any visas for his Russian passport.

Officials “seized both of his passports and ordered him to stay in the terminal until further notice,” Court Watch noted, but “Ochigava did not stay in the terminal.”

Instead, he began trying to board flights, first one to Bangkok and then another to London. Those flights turned him away, but a Scandinavian Airlines System flight to LAX let him through. Officials believed he accomplished this by yet again tailgating a passenger, following them through the boarding gate and onto the plane.

Ochigava’s trial on stowaway charges is set to begin next week, Court Watch reports, but his case could have reverberations beyond just this one instance.

European and American officials have expressed frustration as to how Ochigava was allowed to travel after he was contacted by police and had his documents seized, as has Scandinavian Airlines.

“SAS asked Copenhagen Police why the person wasn’t kept in custody with them as opposed to being allowed to wander, and the response seems to be that there isn’t a legal basis to hold him (SAS expressed surprise at this),” the filings say.