The sister of a “vulnerable” man found dead a week after being reported missing has said the circumstances surrounding his death do not add up.

Dennis Farnell’s body was found in a drainage canal near John Sayer Close, about 350 yards from his home in Stanley Avenue, Barking, on December 28.

The discovery of the 62-year-old was made by police after the retired railway engineer was reported missing on December 21.

His sister, Sylvia Boorman, speaking at the inquest into her brother’s death at Walthamstow Coroner’s Court on July 20, said: “Why was he in that area? Why would he go there? It doesn’t add up.”

The court heard Mr Farnell stopped working 10 years ago after he was diagnosed with depression following the death of his mother.

On May 10 last year he suffered a seizure and was admitted to Newham University Hospital. Around that time a group of people moved into his one bedroom flat.

“Dennis was very vulnerable and they took advantage of [him] as they had nowhere else to live,” Mrs Boorman said. Her husband, James Boorman, confronted the group, telling them to leave after he discovered they were at the flat while visiting in September.

Mrs Boorman told the court Dennis was “on good form” when she delivered his Christmas presents seven days before he went missing.

GP, Dr Jason John, described Mr Farnell as “relatively stable” on his medication in evidence read in court.

An autopsy by forensic pathologist, Dr Ashley Fegan-Earl, found no signs of external injury indicating deliberate self-harm.

But a toxicology report found the level of sleeping pill zopiclone in his body was 10 times higher than it should be for someone prescribed the amount he was.

The level of anti-psychotic drug olanzapine was about ¾ the amount of a fatal dose.

However, a combination of both drugs would not be enough to cause Mr Farnell’s death, although it may have caused him to become drowsy or confused and fall into the ditch, the court heard.

The most likely cause of death was given as drowning linked to hypothermia and intoxication from zopiclone.

Mr Farnell had been reported missing by a woman who had been living at his flat.

Initially assessed a medium level of risk, Mr Farnell’s missing person status was raised to high after his mobile phone appeared.

The woman who reported him missing bought it from her mother - who also used his home - but contacted police after she discovered it was Mr Farnell’s.

The mother claimed she picked it up after seeing Mr Farnell drop it when drunk. But the daughter accused her mother and the older woman’s boyfriend of having something to do with the disappearance.

The court heard that when the mother and daughter met at the police station, the younger yelled, “Tell ‘em what you done”.

But the court heard the allegations she made weren’t based on solid evidence.

The mum told police she picked up the phone while travelling on a bus with Mr Farnell on December 20.

However, CCTV footage was unable to prove whether he was there.

A neighbour later told police he woke up at 2.18am on December 21 to see Mr Farnell entering their building.

Three hours afterwards he noticed Mr Farnell’s door open, though the court heard it was not unknown for him to do that.

On December 25 an informant contacted police to report hearing someone saying, “The body is dead”, as they tried to get into Mr Farnell’s flat. However, police could not confirm who the suspect was.

Three days later officers discovered Mr Farnell’s body half-submerged in the drainage canal.

The investigating officer told the coroner charges could not be made against any of the suspects because there was no forensic or phone evidence linking them to the scene.

The officer agreed after Mr Irvine said: “There are some suspicious elements to this case and I suspect you aren’t particularly happy with some of the information you are provided with, but at the end of the day, you have to have solid evidence with which to mount a prosecution.”

Mr Irvine added there was probably more to the case than meets the eye.

He dismissed the idea Mr Farnell deliberately took an overdose to end his life, with Mrs Boorman saying her brother’s medication regulated his mood.

Mr Irvine, after giving an open verdict, offered his condolences to the family saying the unanswered questions of a “tragic case” must leave them with lingering doubt and only increase their grief.