O'Malley said he noticed pills strewn about the floor and on a glass table. He also found what appeared to be a suicide note signed by Kwiatkowski.
"Please call [redacted] and let her know I've passed away," it said. "Tell her I couldn't handle this stress anymore."
Officers took six medication bottles from the room and transported Kwiatkowski to a nearby hospital, where he was arrested a week later.
Exeter Hospital employees discovered the outbreak in May 2012, prompting an investigation that spanned several local, state and federal government agencies, including the FBI, according to court documents obtained by ABCNews.com.
Investigators wrote that they suspect Kwiatkowski grabbed the loaded Fentanyl syringes when he brought lead aprons into the procedure room, into an area he didn't need to be inside at all. They suspect Kwiatkowski then replaced the syringes of Fentanyl, which is more powerful than morphine, with saline syringes that were tainted with his strain of hepatitis C.
Kwiatkowski was known for erratic behavior and suspected of abusing controlled substances, according to the affidavit. Other hospital employees said he would often sweat through his scrubs and made frequent trips to the bathroom.
One employee told investigators she saw "fresh track marks" when she tried to draw his blood. Another told investigators he remembered seeing Kwiatkowski with "a red face, red eyes and white foam around his mouth" during a shift at the lab.
Kwiatkowski also had a tendency to lie, employees told investigators. He told coworkers that he played baseball in college, and that his one-time fiancée died "under tragic circumstances," neither of which were true. He also once excused bloodshot eyes by saying he was crying all night about a dead aunt who never existed.
When his roommate inquired about the needles in his laundry, Kwiatkowski told her he had cancer and was being treated at Portsmouth Regional hospital, according to the affidavit. Investigators found no documentation to prove this.
In 2008, Kwiatkowski was fired from his contract job at the University of Pittsburgh Medical Center after he was found in an area to which he was not assigned, the New Hampshire Union Leader reported Friday. Two years later, he was fired again, this time from his job as a radiation technician at Arizona Heart Hospital in Phoenix after he was discovered unconscious in a locker room, with syringes and needles on his body, according to the Union Leader.
Kwiatkowski was arrested on July 19 in Massachusetts, where he was being treated at a hospital. He faces up to 24 years in prison. Each offense could also result in a $250,000 fine.
ABCNews.com reached out to Kwiatkowski's lawyer this morning, but he was unavailable for comment.