BANGOR (AP) — A man who mailed poisonous potassium cyanide to a suicidal English man, killing him, was arrested on Wednesday, court documents show.

Sidney Kilmartin sent the poison to Andrew Denton, of Hull, England, in 2012, resulting in Denton’s death, papers filed with the U.S. District Court said.

British authorities investigated in conjunction with American agents after learning Denton, 49, had ordered the cyanide over the Internet to commit suicide after struggling with depression, according to a newspaper report in Denton’s hometown last year. Potassium cyanide is a highly toxic, colorless salt often used in gold mining and electroplating, and exposure to it can be rapidly fatal.

The court papers say Kilmartin, of South Windham, mailed the poison “with the intent to kill or injure another.”

Kilmartin is charged with mailing injurious articles and mailing injurious articles resulting in death, the latter carrying a maximum penalty of life in prison upon conviction.

Authorities arrested Kilmartin on Wednesday morning, and he was in custody in Bangor, U.S. Attorney Halsey B. Frank said. Kilmartin, who was unavailable for comment while in custody, was due to make an initial court appearance, including an arraignment, later on Wednesday, Frank said.

Kilmartin, 52, could have faced the death penalty if convicted, but U.S. Attorney General Eric Holder intervened and declined to seek it in this case, the Portland Press Herald reported.

Frank said the court is having difficulty finding Kilmartin an attorney. An attorney with the Office of the Federal Defender said the office is not representing Kilmartin. A message left by a reporter at a phone number listed as Kilmartin’s home was not returned.