37-year-old Adam Nauveed Hayat of Denver, Colorado, is under arrest and facing federal charges after police allegedly discovered pipe bombs in the safe of his hotel room.

The details surrounding Hayat’s arrest are somewhat confusing, as many of the authorities involved cannot speak on the record yet, but the Denver Post describes him as an “American citizen of Pakistani descent” who was “found with knives after apparently flying to Los Angeles.”

According to ABC News in Denver, the police were suspicious of the incredibly large bill Hayat ran up at the Sheraton Hotel in Denver, where he was staying before he flew to Los Angeles. His father Sultan Hayat says the police told him that Adam had been staying at the hotel since December 26, and his bill was over $10,000.

His failure to settle the bill seems to be what brought him to the immediate attention of hotel staff and then law enforcement. A hotel spokeswoman made a vague reference to “suspicious activity” in the Denver Post report. None of the reports on the case available as of Friday afternoon suggest he was already a person of interest in an ongoing investigation; several note that he has no prior arrest record, although ABC News found court records indicating he was cited for violating a park curfew in 2012.

When investigators checked the hotel room, they found a note written in lipstick on the mirror “referencing PTSD and pipe bombs in the room’s safe.” This led them to track the cell phone Hayat was still carrying and arrest him at a Holiday Inn in Los Angeles.

He was apparently carrying knives at the time of his arrest. His father said police told him that Adam had purchased firearms, but there are no references to guns in the early reports of his arrest. According to his father, Adam has been collecting hunting knives since he was a child.

The police say did indeed find unexploded devices in Hayat’s Denver hotel room. More specifically, KUSA News reports they discovered “roughly six pipe bombs.” The FBI is now involved in the case.

Fox News in Denver reports that up to 20 rooms in the Sheraton hotel were evacuated for a short time after the bomb squad was called in. The pipe bombs were removed in a concrete carrier.

The Marines confirmed to KUSA News that Hayat “served as a machine gunner and military policeman between June of 1999 and July of 2003,” plus he served in Operation Iraqi Freedom in 2004. He left the Marine Corps with the rank of sergeant and is described as earning “a number of awards” during his service.

Sultan Hayat told reporters that his son has a history of mental health problems, including bipolar disorder and ADD symptoms, in addition to post-traumatic stress disorder. He described Adam as “homeless” and said he had been estranged from the family for years. ABC News reports finding him registered to work at a Colorado landscaping firm in 2013, using the address of a Denver homeless shelter.

KUSA relates an anecdote of interest from 2011:

Sources confirmed that Hayat is the same person who appeared in a 2011 story in St. Louis’ Riverfront Times about the “occupy” movement. At that point, Hayat said he was living in the St. Louis area and described himself as an “unemployed Iraq War vet.” “I lost my job waiting tables two years ago after a series of breakdowns,” the Riverfront Times quoted him as saying. “I want the president to look into the backlog of disability claims at the veterans administration. I’m here on behalf of all veterans who deal with Gulf War Syndrome.”

The Riverfront Times ran an article about Hayat on Friday which mentioned that his father Sultan is a cardiologist practicing in the St. Louis area.