Sidney Kilmartin. Credit: Courtesy of the Cumberland County Sheriff's Department

BOSTON — The 1st U.S. Circuit Court of Appeals has vacated a witness tampering charge against a Maine man convicted of mailing fatal cyanide to an Englishman.

But the decision, dated Friday, doesn’t change the 25-year prison sentence for Sidney Kilmartin. He’s serving a separate 25-year sentence for mailing the fatal dose of cyanide, along with several concurrent 20-year sentences on other counts.

It’s unclear whether the U.S. attorney for Maine will seek to retry Kilmartin on the witness-tampering count. A spokesman declined comment Monday.

Law enforcement officials have said Kilmartin posed as a goldsmith to obtain cyanide, which he offered to sell to people on suicide-related chatrooms online. They have said he ripped off the buyers by shipping harmless Epsom salts.

One customer, Andrew Denton of Hull, England, complained to the FBI about the scam, and Kilmartin eventually sent him real cyanide to get him to drop his complaint. The man used the cyanide to take his own life.

Kilmartin is currently serving his sentence at a detention center in Lexington, Kentucky. His lawyer was out of state and couldn’t be reached.