A defence counsel has told a civil trial being held in Darwin that an Aboriginal man who was found hanging in a jail 20 years ago died from foul play.

The body of Douglas Bruce Scott was found in a Darwin jail in 1985.

A coronial inquest found Mr Scott committed suicide but his widow, Letty Scott, believes he was killed by four prison guards.

A civil trial began in the Northern Territory Supreme Court today, with Mrs Scott attempting to have the original inquest findings overturned.

In court today, the parties agreed to pursue the civil trial in its entirety rather than apply for a new coronial inquest.

Defence counsel Daniel Taylor told the court an eyewitness would give evidence that he saw four prison guards enter Mr Scott's prison cell.

Mr Taylor said the witness later heard screaming coming from the cell.

He also told the court that Scott could not have reached the ceiling grill to tie a noose. He said a stool was placed in the cell after Mr Scott was found dead.

But he said the stool was not in a position to have been used by Mr Scott.

The trial is expected to continue for two weeks.