Alaska serial killer Israel Keyes has now been linked to more murders than he confessed to before his death, authorities say, and they expect to connect him to even more unsolved killings before they’re done.

Keyes slit his own wrists in his jail cell in December after confessing to the murder of Alaskan barista Samantha Koenig and leading police to her remains. He also confessed to seven other murders, which have now been confirmed, and gave authorities vague clues about others he took credit for. Based on his statements, they were able to connect him to three other killings across the U.S.

Police and FBI have been working for months to piece together the clues they had and say they’ve dug up at least two caches of weapons, cash, and tools that Keyes hid for his own later use. Because he traveled extensively during his search for victims, they fear there may be unsolved murders in other countries that are tied to him but lack the evidence to prove it. They are asking the public to come forward with any information about Keyes and his travels, saying they know he made trips to Montreal to seek out prostitutes.

“If we have a missing person identified in a particular area, we work closely with that local police department to either connect the person to Keyes or not,” Jolene Goeden, FBI special agent in Anchorage, said in a statement. “We have his DNA.”

Keyes left a four-page note before killing himself, but it doesn’t offer many clues as to why he committed the murders. It does, however, offer a glimpse into the mind of a man who was filled with disdain for other humans.

I looked in your eyes, they were so dark, warm and trusting as though you had not a worry or care. The more guiless (sp) the gaze the better potential to fill up those pools with your fear,” Keyes wrote. “Your wet lips were a promise of a secret unspoke. Nervous laugh it burst like a pulse of blood from your throat. There will be no more laughter here.”