“I always say my dad died twice. I lost my dad to a heart attack when I was six. And I lost my dad to murder when I was 16.”

“And that opened a really big can of worms in my life.”

Madison (right) learned when she was 16 that her father (left) hadn’t died of a heart attack when she was little but had in fact been murdered. Source: Supplied

She began by interviewing friends and family, convinced someone close to the family must have answers.

“I had some people who were suspiciously supportive at the time, and some people who were really adamant that I should let it go.”

Power of the public

“I didn’t feel like it was taken seriously,” she told Insight.

Haylee (right) says she decided to investigate her brother’s disappearance when she felt the police “didn’t take it seriously”. Source: Supplied

. She set up a Facebook group, which attracted the attention of a search and rescue dogs provider. With their help, she coordinated a large-scale search of the bushland near Nannup in Western Australia, where Corey’s car had been found.

She had seen some bones.

Haylee believes she would never have found her brother’s remains without the help of citizen sleuths. Source: Supplied

The drone operator provided the coordinates, which eventually led police to her brother’s remains.

“I wouldn’t have found Corey if it wasn’t for them.”

When sleuths are a hindrance

“How do they actually wade through them to determine what may be useful?”

“Information being shared during court cases, for example, that can make that highly problematic.”

“I understand why people want to get involved in cases, especially those they feel a personal connection to, when they haven’t received the answers that they need.”

Sleuths ‘bring a fresh set of eyes’

“When I’m on the road at work, there’s a lot of time to kill,” he told Insight.

“I enjoy just looking into cases that maybe the police have missed stuff on.”

During his long hours on the road as a truck driver, Trevor ponders cold crime cases. Source: Supplied

Despite being adamant about the validity of his theory — which has never been proved, Trevor says his investigation is at a standstill.

“I can only do so much without being a detective or law enforcement.”

Trevor has been fascinated by Australia’s cold cases since he was a child. Source: Supplied

Trevor says it’s disappointing his information didn’t have more impact because he’s doing research where others lack the resourcing.

“And I want to help give them answers.”