A U.S. resident accused of mailing cyanide to a suicidal resident of England has pleaded guilty to some of the charges against him and will stand trial on others.

Sidney Kilmartin, of Windham, Maine, changed his not-guilty plea on wire and mail fraud charges to guilty Monday.

His trial was scheduled to begin later Monday on charges of mailing injurious articles resulting in death, witness tampering and witness retaliation. He pleaded not guilty to those counts.

Investigators say Kilmartin advertised and mailed a substance he claimed was cyanide to several suicidal people. The substance was actually Epsom salt.

They say he mailed the real thing to Andrew Denton, who then used the cyanide to kill himself.