The New York felon who set a Christmas Eve trap for firefighters left a note saying he wanted to burn down the neighborhood and "do what I do best: killing people," reports the Los Angeles Times. Investigators found human remains in the burned-out home of ex-con William Spengler, 62, a day after his rampage in Webster, a Rochester suburb. Officials said the remains probably were those of Spengler's missing sister, Cheryl, 67.

Spengler apparently set the blaze in or near his home and lay in wait, killing two firefighters and seriously wounding two more before taking his own life, officials said. In his note, Spengler wrote, "I still have to get ready to see how much of the neighborhood I can burn down and do what I do best: killing people," police said at a Christmas Day news conference. Spengler appeared to have led an uneventful life for the last 14 years, but had a violent history: In 1980, he beat his grandmother to death with a hammer. He spent 18 years in prison and was released in 1998. On Monday, Spengler apparently used a military-style Bushmaster .223 rifle. Assault rifles also were used Dec. 14, when Adam Lanza killed 20 grade-school students and six adults at a Connecticut school, and on Dec. 11, when Jacob Roberts opened fire in a Clackamas, Ore., mall with an AR-15-style rifle, killing two and wounding one before taking his own life.