UPDATED 5.53PM: Fellow officers are slamming a crooked cop, jailed today for stealing evidence.

Former Whangarei detective Michael Blowers has been sentenced to four years and nine months jail, for stealing methamphetamine and supplying it to a drug dealer.

Police Association president Greg O'Connor says local officers feel betrayed, particularly because it led to some drug offenders walking away from charges.

"Knowing that you've got some serious criminals up there and it's not easy to find these guys, get the evidence and particularly get the drugs themselves on them.

"That's the result of some serious hard work."

Detective Inspector Allsopp-Smith says by stealing the drugs, Blowers tampered with evidence and caused a case to be dropped against two serious offenders caught with over 50 grams of meth.

He says police a lot of effort into making the community safer.

"This sort of activity by Mr Blowers strikes at the heart of all the efforts that they're putting in in the community."

Blowers' family feels the pressure

The family of the former Northland police detective is feeling the pressure following his conviction for drug offending.

During sentencing Justice Venning, told Blowers his fall from grace has humiliated his family and both emotionally and financially strained them.

Justice Venning says Blowers will have to cope with these consequences for some time.

Blowers has a wife of 24 years and two adult children.

Changes made to Whangarei police station

Changes have been made at Whangarei police station following the conviction of a former detective.

Michael Blowers was sentenced in the High Court at Whangarei this morning for stealing methamphetamine from a police store room and then supplying it to a female dealer.

Superintendent Russell Le Prou says an independent review has conducted into the drugs exhibit handling at the station.

"That has caused some small charges but essentially we found that our procedures and processes were sound, but again, we have changed some things and we don't have that exhibit store anymore."

Blowers sentenced to four years, nine months

A former Northland police officer has been sentenced to four years and 9 months imprisonment on drugs charges.

Michael Blowers appeared in the High Court at Whangarei for sentencing this morning.

He'd admitted stealing methamphetamine and then supplying it to a drug dealer.

Blowers' fall from grace comes after 21 years in the police force.

The court heard today of how a case was dropped after Blowers stole the meth which was to be used as evidence.

Blower's defense lawyer, Arthur Fairley says Blowers accepts it was his fault the case was dismissed.

"The methamphetamine has to be accepted as methamphetamine by the accused person, and or if it's not it has to go to the ESR to be proved," he said.

"Because Mr Blowers was a link in the chain, if you take out that link, they couldn't prove it was methamphetamine."

Arthur Fairley says Blowers is deeply ashamed of his actions.