A guard who smuggled drugs and glue into an Adelaide prison was worn down by a "slow-burning crisis of faith in his employer", a court has heard.
Michael Charles Asker, 66, says he was a model employee for years but his attempts to help the prison population were poorly received.
Asker, who served in the army before joining the Department for Correctional Services in 1992, has pleaded guilty to one bribery charge arising from an investigation by the Independent Commissioner Against Corruption.
Defence counsel Michael Jandy told the District Court on Wednesday that Asker was "viewed with suspicion" by other employees for jail programs he ran, including cooking and first aid classes.
"He was a proactive worker.... he was interested in the welfare of prisoners," he said.
"He was indeed criticised consistently by colleagues for being too much of a social worker."
While working at the Adelaide Women's Prison, Asker was disciplined for failing to notify management that he had received an offer to start a brothel with a prisoner.
He was eventually moved to the Yatala Labour Prison after he was found with a love letter written by a prisoner to "Mr amazing eyes".
"Any seeds of discontent that he had with corrections were fertilised here (at Yatala)," Mr Jandy said.
"He weakened... it was a slow-burning crisis of faith in his employer".
Asker was initially asked to undertake small favours but eventually met a prisoner who wanted him to do "anything and everything" to bring in "whatever he could".
In September 2018 he received and delivered a hamburger bag full of the prescription opioid Suboxone into the prison.
Asker also took in glue, which could have been used to reseal food packaging to make it appear as if it had not been opened.
A few days later he collected a cash payment of about $250, before he received $500 and another parcel in December of that year.
That parcel, which contained methamphetamine and a prescription drug, was later found by police in Asker's car.
Mr Jandy said Asker would be met with hostility in jail because of his job as a prison officer, and asked Judge Liesl Chapman to hand him a suspended or home detention sentence.
Judge Chapman continued Asker's bail ahead of sentencing in May.