Not only was it his 65th birthday, the Launceston Senior Constable reluctantly retired from Tasmania Police after 43 years' service.

Since graduating in April 1971, he worked in traffic patrol and the fire investigation unit, but has spent the past 30 years with forensic services - his dream job.

But a police officer must retire from duty once they hit 65, as stated by the Police Service Act 2003.

"I wanted to get involved in forensic work or as it was called then, the scientific bureau," he said.

"I was a keen photographer, so that was a fairly important part of it and the crime scene examination of it was something I wanted to learn about.

"I was was accepted [into forensics] after about 13 years in the job."

The father of five said his favourite and most celebrated case was a Bicheno post office burglary, where he gathered evidence that eventually forced a suspect to admit guilt.

He said the offender used oxygen-acetylene equipment to cut the post office safe door open and, after analysing the composition of the acetylene and oxygen residue on the metal, he was able to link the evidence.

"We had information to suggest who the person may have been ... but there was no DNA or fingerprint evidence at the scene," he said.

"I came up with the idea of comparing the metal prills that had come away from the door as it was cut and matched it with the metal prill found melted in the sole of the shoe of the suspect.

"We were not going to proceed because we didn't have enough evidence, but when that evidence came out, that person pleaded guilty - I was really pleased I put that away."

Two of Mr Midson's brothers were also police officers and now his son has followed him into the force, which he said filled him with pride.

He said he would miss the people he worked with and being among crime scenes, but said he would not miss the stress of going to court.

He said he had learnt a lot over the past four decades, especially about people.

"I'm amazed at how silly people can be at times and create their own problems and don't seem to have the foresight to recognise situations they are going into to be dangerous," he said.

"I have learnt a lot from their mistakes."