Police say Blowers, who had 20 years of policing experience, all of it in Northland, stole methamphetamine from the Whangarei police station drug store room on or about October 19, 2011.
He is then alleged to have tried to cover up the theft by replacing the white-powdered drug with table salt.
However, defence lawyer Arthur Fairley said in a brief address that Blowers strongly denied he stole drugs or supplied them. Mr Fairley said Blowers had made a loan to the woman and "was most interested in getting it back" but it was not drug money.
"He will say he certainly did not give her methamphetamine or cannabis."
Mr Hamlin told the jury of seven women and five men the woman became Blowers' drug dealer and that they developed a commercial drug-dealing relationship. Without her help, Blowers would not have been able to make the money he did, the court was told.
Discovery of the drug network being run by Blowers was accidental, Mr Hamlin said.
Blowers was undergoing a review of his employment in 2011 after it was discovered he was breaching police procedures around the correct recording and storage of drugs, particularly methamphetamine, in two special drug stores at Whangarei police station.
"He wasn't following the rules," Mr Hamlin said.
Blowers had limited access to the drug store in the main body of the station where most of the seized methamphetamine was "posted" in an envelope through a locked door. However, he had unlimited and unsupervised access to the bulk drug store where bigger items including large amounts of cannabis were kept.
Mr Hamlin said Blowers had been putting methamphetamine in the bulk store and had been told by his superiors to stop.
Six months later he was moved to the child-protection unit and there were no suspicions about the missing drugs.
When police were preparing for a trial relating to the seizure of 58 grams of methamphetamine from Whangarei motel Burgundy Rose, they noticed a discrepancy in the purity of methamphetamine that had been tested. Initial tests had shown it was 81 per cent pure and a second test showed 29 per cent purity and that table salt was present, Mr Hamlin said.
"It looked the same, it weighed the same but it was not the same."
He said that two days after the drug seizure at the motel, records showed Blowers had removed the methamphetamine from the drugs store and taken it to the bulk drug store, then a day later put it back: "Blowers deliberately stole the meth and covered up with table salt."
On April 6, 2013, Blowers denied any drug dealing but said he had pretended to be a drug dealer and sent the woman text messages demanding money.
About 40 witnesses are expected to give evidence in the trial, many of whom worked with Blowers. The woman is to give evidence against Blowers and is subject to wide suppression orders.