A man who is already serving a lengthy prison term has had more jail time added for a sex attack on a prostitute.
The offending was picked up only because of advances in DNA testing.
Justice Brewer told Sumit Narayan in the High Court at Auckland on Tuesday he was a dangerous man and would be ordered to serve preventive detention if the law allowed.
Narayan was 19 in 1997 when he pulled up in a car alongside a prostitute in Auckland on 27 December.
He used a stun gun to shoot the man she was with and ordered the pair out.
Justice Brewer says Narayan made the man lie on the ground without pants before taking off with the woman and making her perform a sex act.
"You threatened the prostitute; told her to say that if she was asked that she had been assaulted by a client. You told her if she told anyone you would shoot her and you said you knew where she lived."
Narayan is nearing the end of a 15-year term for a sex attack and aggravated robbery in 2000.
He was originally given a sentence of preventive detention but this was changed after an appeal.
Justice Brewer wanted to impose a similar sentence. "I judge you to be a dangerous man. If I could I would sentence you to preventive detention but I cannot. You were too young at the time of the offending."
In sentencing Narayan to a further seven years in prison, Justice Brewer said Narayan showed a lack of empathy, remorse and understanding.