American with history of mental illness arrested in connection with cyanide suicide of Hull man

Toxicology report ruled cyanide as the cause of Andrew Denton's death which was allegedly traced back to US individual who he communicated with

An American man with a history of mental illness has been arrested in Maine in connection with the cyanide suicide of a Hull individual in 2012 following a transatlantic investigation.

Sidney P. Kilmartin, 52, pleaded not guilty to the charge of sending potassium cyanide to Andrew Denton, 49, who was found dead in his Hull home on New Year’s Eve 2012 by his niece Gail Coates.

A toxicology report confirmed Mr Denton died from cyanide poisoning, which it is alleged he obtained from Kilmartin after the two exchanged messages online.

If convicted, Kilmartin could face 20 years to life in prison.

Ian Dobson, leader of Humberside Police's Critical Incident Team, said in a statement, "This is a great example of international law enforcement agencies joining up”.

The American connection was discovered following coroner Rosemary Baxter’s verdict of suicide when Humberside police decided to trace the origin of the potassium cyanide.

After analysing Mr Denton’s mobile phone, laptop and other electrical devices they found messages from him to an anonymous individual in Maine. Humberside police contacted the FBI, who handed the investigation on to the postal inspection service.

Postal inspector Michael Desrosiers, who visited Hull in June in order to conduct interviews with witness and request them to appear in the US, said to the Hull Daily Mail: "In my 28 years as an inspector, I have never come across potassium cyanide being mailed and it is even rarer it has led to a death.”

The messages revealed Mr Denton, who allegedly struggled with depression for years prior to his death, had attempted to kill himself before but failed after he was sent a faulty batch. He allegedly received another shipment from Kilmartin and managed to kill himself.

Appearing in court earlier this week, the Portland Press Herald reported Kilmartin appeared confused, saying: “It’s kind of overwhelming right now.”

His lawyer Jeffery Silverston interrupted him before he could enter his plea to Magistrate Judge John Nivison, amending it to one of “not guilty by reason of insanity”.

Kilmartin is now in custody at Somerset County Jail and his case will be heard on Friday next week.

It remains unclear how the cyanide allegedly sent to Mr Denton was obtained.

Potassium cyanide is a highly toxic, colourless salt, similar in appearance to sugar, used commercially, but which releases highly toxic hydrogen cyanide gas which interferes with the body’s ability to use oxygen.

Swallowing the chemical causes nausea, vomiting, abdominal pain and irritation or corrosion of the lining of the oesophagus and stomach. Exposure to as little as 200 milligrams – about the size of paracetamol pill – can be fatal.

The substance is tightly regulated in the US, however, Dr. Frank Paloucek, a pharmacy professor and toxicologist at the College of Pharmacy at the University of Illinois at Chicago, suggested the chemical might have been obtained illegally from a commercial or industrial producer.

In 2007 Kilmartin was charged for aggravated assault and burglary after he broke into an 86-year-old neighbour’s home and smashed a radio over his head. Kilmartin, who was discovered on the scene by officers, remembered nothing.

The man was hospitalised suffering from a broken jaw, broken eye orbital and cheek bone, bleeding on the brain and a possible fractured rib. Kilmartin was found innocent due to insanity.

While on bail he was discovered in the possession of drugs and in 2008, following a psychological examination, was committed to Riverview Psychiatric Hospital.

It remains unclear if or when he was released from hospital.