POLICE have played down reports that a mother killed herself and her autistic son because she feared a third world war.

Helen Rogan plunged to her death with 11-year-old Mark Owen Young from a County Durham viaduct, on Monday, after telling her family she was worried a new war - following the New York terrorist attacks - could leave her son orphaned.

However, detectives carrying out a murder-style inquiry into the double death, say Miss Rogan's overriding fear, revealed in a series of heartbreaking notes left for her family, was the unbearable strain of looking after a boy with autism.

Mother and son were discovered below the 180ft Gill Bridge viaduct, at Consett, County Durham, by a relative.

Police also concede that they might never know whether Miss Rogan pushed Mark before jumping herself, or if they fell together.

Acting Chief Inspector Simon Orton, part of the investigating team based at Consett police station, said: "She had spoken to her family about events in America and was frightened that, if there was a war and anything happened to her, there would be no one to look after her son.

"However, the biggest fears playing on her mind seem to have been related to the upbringing of her son.

"Of course, she was also concerned about developments in America and the possible outcome - but everyone has been."

Miss Rogan, 38, a qualified occupational therapist, of Robinson Street, Consett, gave up her job to look after Mark several years after she split from his father.

She left several notes explaining her difficulty in caring for an 11-year-old with autism on her own.

The police investigation is being conducted as a murder inquiry, with teams of forensic experts combing her house, gathering evidence to present a file to the coroner.

Chief Insp Orton said: "All we can do is piece together what happened immediately before their deaths.

"Unfortunately, unless a witness comes forward, we will never find out the true sequence of events that occurred on that bridge.

"They are the only two people who know that."

An investigation into the case by Durham Social Services is continuing.

Anyone with information about the incident is asked to contact Consett police on (01207 504204.