A Windham resident has been convicted of mailing cyanide to a man in England, which resulted in the man’s death.

According to a news release from Assistant U.S. Attorney Halsey B. Frank, Sidney Kilmartin, 54, faces up to life in prison and a $250,000 after being found guilty in a six-day jury trial in U.S. District Court. He also was found guilty of wire fraud, mail fraud and witness tampering, and faces up to 20 years in prison and fine of $250,000 on those charges.

Kilmartin offered to sell potassium cynanide on a website devoted to suicidal people, according to court documents. Between 2012 and May 2013 he accepted payments from people through PayPal, the documents said, and to some of the buyers he sent Epsom salts instead of the promised cynadide. When one recipent of the Epsom salts, the Englishman, did not die after taking the dose, he complained to Kilmartin and to law enforcement. Kilmartin then sent the man cyanide that resulted in his death.

Kilmartin was found not guilty of witness retaliation. He pleaded guilty to related wire and mail fraud charges.

Kilmartin will be sentenced after the U.S. Probation Office completes a presentence investigation.