A former firefighter has pleaded not guilty to arson charges in the blaze that damaged the western New York apartment of a volunteer firefighter who said he received a racist, threatening letter earlier this week.

North Tonawanda police say 39-year-old Matthew Jurado was arrested Thursday and charged in the fire at 28-year-old Kenneth Walker’s home. WGRZ-TV reports Jurado is Walker’s neighbor and the two know each other.

A judge entered a not guilty plea Friday morning for Jurado because he didn’t have an attorney for his arraignment. He’s being held in jail on $50,000 bail.

Police say Jurado confessed to setting the fire. But they say he didn’t claim responsibility for an anonymous letter that Walker said was left in his mailbox on Monday. It told him to resign because he’s black.

Investigators say Jurado told them a friend of his was behind the letter.