Steven Hayes, the man sentenced to death last December for his role in the 2007 Cheshire home invasion murders, bragged in a letter from death row that, prior to the Cheshire murders, he had killed 17 women and collected his victims’ sneakers as trophies.

The New Haven Register reported it had obtained a copy of that letter Sunday, though it has not been publicly released and the newspaper did not specify how it was obtained.

“Yes, I’ve killed before,” Hayes wrote in the letter. “I have 17 kills throughout the Northeast United States. Perfect victims and well executed, controlled endeavors.”

Hayes also wrote four letters to a North Carolina recipient identified only as “Lynn”, according to the Associated Press. In those letters, he similarly claims to have killed 17 people, adding that he has committed several sexual assaults of drugged victims in motels and taped 16 hours of a kidnapping and assault.

Hayes and Joshua Komisarjevsky have been convicted of murder, sexual assault and other offenses in relation to the July 2007 deaths of Jennifer Hawke-Petit and her daughters, Hayley and Michaela. For those crimes, Hayes has received six death sentences and 106 years imprisonment. Komisarjevsky was found guilty Oct. 13 and is awaiting sentencing.