Nobody really knew what to make of William Spengler after he set his house on fire and then proceeded to kill two firefighters who arrived on the scene. In a new note found by investigators, we now know that the killer fully intended to kill a lot more people before he was stopped by law enforcement.

The AP reports that Webster Police Chief Gerald Pickering held a news conference on Tuesday revealing that his department’s investigation found a note left by Spengler. The note laid out the killer’s plan of burning down his entire neighborhood and killing many more people than the two firefighters and his sister that lost their lives on Monday. Pickering noted that Spengler’s writing was mostly incoherent rambling, but it did contain one rather disturbing line – “I still have to get ready to see how much of the neighborhood I can burn down, and do what I like doing best, killing people.”

Investigators are still trying to piece together what caused Spengler to go off on Christmas Eve, but this isn’t the first time that he’s been involved in violence. He was charged in the death of his grandmother in 1980, but only served 17 years after reaching a plea bargain that reduced his charge to manslaughter. After getting out of prison, he lived with his sister and mother. Some speculate the death of his mother in October, whom he reportedly loved very much, may have set him off. The investigation is still ongoing, however, and may reveal more insight into what caused Spengler to snap on Christmas Eve.