The grisly crime that touched Peter Dutton will change the way you see him.

Long before Peter Dutton took a stab at becoming Australian prime minister, he was a young police officer in Queensland who became involved with one of Australia’s most devastating child murders.

Deidre Kennedy was born on November 22, 1971, the second daughter of Barry and Faye Kennedy.

On April 13, 1973, Deidre was just 17 months old when she was was taken from her cot. Her body was discovered the next morning on the roof of a toilet block in Ipswich’s Limestone Park.

She had been strangled, bitten and sexually assaulted before her death. Fairfax Media report it is remembered as one of the most heinous crimes to rock Queensland.

Dutton joined the Queensland police force in 1990, aged 18. He worked as a detective on Deidre’s murder, for which the same man – Raymond John Carroll – had been found guilty and acquitted twice.

In 1985 Carroll was found guilty by a jury and given a life sentence, but after an appeal the conviction was quashed.

Queensland’s double jeopardy laws meant he could not be tried again for the murder, even after new evidence linking him to the crime was found in 1990.

Prosecutors decided to try Carroll for perjury, claiming he had lied on the murder trial when he said he had not killed Deidre.

In 2002, a Supreme Court jury found Carroll guilty of perjury. But this conviction was quashed again on appeal less than a year later.

This was a disappointing result for Dutton, who had been working on Deidre’s case for more than a decade. The case then led to a lengthy campaign to change the state’s double jeopardy laws – led by Deidre’s mother and Dutton.

Thirty years after the toddler’s death, the two launched a petition calling for the law to be changed and in 2006 they embarked on a road trip from Cairns to the Gold Coast to gather more than 100,000 signatures.

They presented the petition to then-Queensland premier Peter Beattie and changes to the law were passed in October 2007.

The changes allow an acquitted person to be retried if new evidence comes to light, but only applies to crimes committed after 2007.

In 2014, then Queensland attorney-general Jarrod Bleijie made changes that allows a person to be tried for the same crime, regardless of when it was acquitted.

Despite this, Carroll remains free. Fresh evidence will need to be found if he is to be retried a third time, according to a blog post by Melbourne Law School professor Jeremy Gans.

A source close to the Kennedy family told Fairfax Media they held Dutton “in the highest esteem”, and called him “the driving force” behind the campaign to change the laws.

Dutton spoke of his time as a police officer in his first speech to Federal Parliament in 2002 and spoke of his tough-on-crime stance.

“I often say to people that, as a police officer, I have seen the best and worst that society has to offer,” he said in the speech.

“I have seen the wonderful, kind nature of people willing to offer any assistance to those in their worst hour, and I have seen the sickening behaviour displayed by people, who, frankly, barely justify their existence in our sometimes over-tolerant society.”

The laws Dutton helped update were enacted for the first time just last month, when a man was arrested in relation to a murder in the 1980s.