THE NSW Director of Public Prosecutions has dropped investigations into the death of profoundly autistic Canberra teenager Jack Sullivan more than four years ago.

Almost two years since the case was passed to the DPP, the public prosecutor says it does not have enough evidence to press manslaughter charges against a person whose name has been suppressed.

Since Jack's death, his mother, Esther Woodbury, had assumed her son drowned in a bath after an epileptic seizure while in outside care.

She said she believed he was brought back to life by a medical crew, fell into a coma and had his life support switched off at Canberra Hospital.

In October 2010, the coronial inquest into Jack's death was suspended.

At the time NSW Deputy State Coroner Hugh Dillon said he had suspended proceedings because a person may have committed an indictable offence that led to the tragedy.

During his speech at the end of hearings in 2010, the coroner suppressed the name of the person and also said there was the possibility the DPP would not go ahead with a prosecution.

Last week a DPP spokeswoman said further information had been sought from medical experts, which concluded that the exact cause of Jack's death could not be specified.

''As a result the causational aspect of manslaughter could not be established beyond a reasonable doubt,'' the DPP spokeswoman said.

''Consequently a charge of manslaughter could not be supported.''

Mr Dillon's finding of ''partial drowning while in the bath'' is now the official and most descriptive cause of Jack's death.

Read more: http://www.canberratimes.com.au/act-news/dpp-drops-sullivan-probe-20120…