Drug-dealer prison guard 'Jekyll and Hyde'

A Perth prison guard who was apparently suffering a "midlife crisis" had a "Jekyll and Hyde" pastime as a dexamphetamine dealer after a marriage breakdown, a court has heard.

Peter David O'Byrne, 58, worked for the Department of Corrective Services for 28 years and most recently the maximum-security Casuarina Prison.

The District Court of WA heard O'Byrne began partying after his marriage broke down and sold each tablet at a $2 premium to ingratiate himself with his new, younger circle of friends.

He was on Thursday sentenced to two years in jail by Judge Ronald Birmingham, who noted he would do time tougher than other prisoners.

O'Byrne will be eligible for parole after serving half of that term.