Tamworth-born killer Scott David Lynn ordered to serve further 15 months in prison

Scott David Lynn, 42, was handed a controversial Continuing Detention Order (CDO) in the NSW Supreme Court after it found his behaviour was so violent that he would pose an unacceptable risk to the community.

Courts can impose CDO's once an offender's term has been served, and the regime enables indefinite detention at the end of a term of imprisonment.

Numerous forensic psychologists have examined Lynn throughout the years, the court heard.

He has never been diagnosed with a mental illness or disability but is said to have a number of personality disorders and substance abuse problems.

"While previous reports have found that Mr Lynn does not suffer from a mental illness, he nevertheless displays a pattern of communication which is unusual, even among high-risk offenders," psychologists Richard Parker and Danielle Matsuo noted in a 2016 report.

"While a hostile interpretation of the world is fairly common in high-risk violent offenders, the pattern with Mr Lynn seems more extreme ..."

The decision to keep Lynn in prison was made on May 17, after the court found he had limited prospects for rehabilitation and could not safely be managed in the community.

In 2006 while on a good behaviour bond, Lynn killed a man after a brief conversation and chance encounter on Parramatta Street.

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The unarmed victim died after Lynn stabbed him in the neck, a hung jury in his murder trial meant Lynn pleaded guilty to a lesser charge of manslaughter and was sentenced to seven years in prison.

"I believe that [the defendant] lacks appropriate insight into his criminality on this occasion, as he does in relation to past offences," Justice Hidden said at the time.

The 18-month sentence Lynn just finishing serving was for minor convictions in the local court.

He was due for parole release in September.

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