Bevan Peter Brown's decision to rob a dairy co-owner at knifepoint to get arrested was a "desperate cry for help", a court has heard.

The 34-year-old Gate Pa man was sentenced yesterday by Judge Louis Bidois, who jailed Brown for 22 months.

Lawyer Rachael Adams criticised the community mental health system for letting Brown down by effectively turning him away when he sought assistance the day before the robbery, describing it as "a very sad indictment on the state of our mental health system".

Last month Brown pleaded guilty to one charge each of aggravated robbery, possession of an offensive weapon in a public place, namely a knife, and threatening to cause grievous bodily harm to a person or persons unknown. The charges stem from two sets of events this year.

On October 8 Brown robbed Colorado Dairy co-owner Mohammed Begg at knifepoint and stole a packet of cigarettes and a lighter.

The day before, he told a mental health care facility manager he was thinking about stabbing someone in a supermarket to get arrested.

Police were called.

Brown was found in possession of a knife walking towards Countdown Greerton where he said he was heading with intention of stabbing someone.

He was bailed by Tauranga District Court on October 8 and later the same day stole groceries from the same supermarket while in possession of a knife.

He then walked across the road and robbed Mr Begg after brandishing the knife.

Brown, arrested a short time later, told a police detective he was feeling suicidal and had homicidal thoughts of stabbing someone in a crowded supermarket.

Crown prosecutor Nick Belton submitted a prison sentence of around four years before discounts for Brown's guilty pleas and other mitigating factors, including his mental health disorder, was appropriate.

But Ms Adams argued for a lesser sentence for what she described as a "quite unique and very sad" set of circumstances.

She told Judge Bidois that this was a "quite a tragic case" where Brown had sought help but in essence was turned away after he was assessed as being not ill enough despite a longstanding mental illness history.

"This is a man who sought help because he knew he was unwell and when he didn't get it, on his release on bail he took the drastic step to ensure he got arrested. That's a very dramatic, desperate gesture.

"He was crying out for help and believed it was the only way he could get the help he wanted, which he is ironically now receiving in prison."

Ms Adams said Brown's offending was in an entirely different category than other armed robberies. "These charges come from a very sad series of events which are the result of Mr Brown's mental illness ... It's a very sad indictment on the state of our mental health system which led him to be in this position today."

Judge Bidois said he agreed Brown's offending was in a different category than other dairy armed robberies, as he did not use the knife to stab anyone, didn't disguise himself nor make any real attempt to get away from police.

The judge said given that Brown was suffering from a significant psychiatric impairment and clearly had a mental health crisis on the day of the robbery and the hours leading up to it, he was prepared to step back from the usual jail sentence.

Judge Bidois said clearly Brown was now receiving the treatment he had asked for and there were good prospects for his rehabilitation.

Last month the Bay of Plenty Times reported the criticisms of police by Colorado Dairy co-owner Muhammed Begg senior, whose son was robbed, for their failure to oppose Brown's bail on October 8 despite his twice disclosing homicidal and suicidal thoughts.

For more articles from this region, go to Bay of Plenty Times