It all started with a UFO sighting.
Dr Horace Drew, 61, was just 10 years old when he allegedly saw an unidentified, silver, windowless craft hovering in the sky near his suburban home, in Jacksonville, Florida. The encounter lasted only moments but led to a lifelong fascination with the extraterrestrial.
"I saw a UFO, so I knew they were real from an early age," Dr Drew told news.com.au.
The scientist, who holds a PhD in Chemistry from Caltech, the California Institute of Technology, and worked for CSIRO as a molecular biologist, has been researching crop circles and aliens for 20 years. Dr Drew relocated to Australia in the 1980s but most of his work has taken him overseas, predominantly to Europe.
"They're quite rare in Australia," he said.
He, along with many conspiracy theorists, believe crop circles are the work of aliens or human time travellers. Sceptics say most are probably man-made.
A crop circle is typically defined by standing wheat stems that have been flattened in the shape of a circle or more complex pattern. They tend to appear mainly in developed Western or secularised countries - including Japan.
The cause of many of the circles is unknown despite various natural and unorthodox explanations having been put forward. Some crop circles have been proven to be hoaxes.
But according to Dr Drew, a number are legitimate and contain puzzles that can be decoded and linked to time travel and alien life.
He told news.com.au he had visited about "two dozen crop circles" around the globe in his career. Typically, they were between 50-500m in length, he said.
"For the past 20 years I have been studying UFOs or crop circles. Just as other mainstream scientists study conventional subjects," Dr Drew told guests at the March UFO & Paranormal Research Society of Australia (UFO-PRSA) seminar in Sydney on Wednesday night.
"This has led to at least one major breakthrough the discovery of a more advanced binary code than our computers currently use."
Dr Drew claimed that aliens or human time travellers have been leaving the crop circles on Earth as messages to "us or themselves".
WHY ARE THERE CROP CIRCLES?
Dr Drew said he was one of a handful of scientists around the world who had worked to successfully decode some of the messages in crop circles.
According to him, some crop circles provide general descriptions of the future.
"Other crop (circles) show schematic images of the future for astronomical or human events," he said.
He said some of the decoded messages read: 'Much pain but still time. Believe. There is good out there'; 'Beware the bearers of false gifts and their broken promises'; 'We oppose deception. Conduit closing'.
Dr Drew has developed at least two theories as to the purpose of the circles by reading their "advanced (version of) binary codes".
"One theory is that they are trying to introduce themselves to us peacefully, like we do using bubbles with dolphins," he said.
"When (humans) want to talk with dolphins we put little bubble circles under the ocean with a generator. We watch the dolphins come up and play and investigate, and we study them.
"This is called the 'dolphin communication project'."
He said the dynamic between the way humans interact with dolphins and whales was likely comparable to how extraterrestrials communicate with us.
"Barack or Trump have never said to a dolphin: 'take me to your leader I want to sign a treaty with you'," he said.
"And (the extraterrestrials are) not interested in making a treaty with us.
"They are ahead of us like we are ahead of the dolphins and the whales."
His second theory was that the messages "are not even for us".
Dr Drew said human time travellers from the distant future could be creating the circles as directional markers, to help them navigate "in their distant past, which is our present".
"There are definitely humans living there in about 5000 years with time travel capability," he said.
"They're coming back and flying all over Earth.
"They seem to just say 'this is a certain day' and mark it.
"So the trouble is we don't know space time physics enough to understand what's happening. It's beyond our knowledge.
"Maybe they don't want us to know about it. It might be just for them."
It's a theory shared by many in his field of work.
HOW ARE THEY MADE?
Dr Drew said the circles appeared to be created by an "unknown energy that heats the crops up".
"It's like microwave energy but is something beyond earth's science," he said.
"It can pattern the wheat.
"No one sees or hears anything and that's why its so hard to prove. If there's a craft, it's silent, noiseless."
But there's nothing to fear, according to him.
"Don't be afraid," he said.
REAL OR A HOAX?
Telling the difference between a real crop circle and a hoax is like differentiating between an original painting and a fake, according to Dr Drew.
"There are some things to look for," he said.
Crops that are bent "halfway up" their stems, rather than on the ground ,is one telltale sign "cereologists", or someone that advocates paranormal explanations of crop circles, look for to determine that it's not a hoax.
"You can't absolutely prove a crop circle wasn't a hoax but you can give a high probability and judgment," he said.
"If there's a hoax the word of it gets around very fast, people are aware, people are not that easily fooled."
In 1991, English pranksters Doug Bower and Dave Chorley took credit for most of the crop circles across southern England made since 1978. They were inspired by the Tully "saucer nest" case in Australia, where a farmer found a flattened circle of swamp reeds after observing a UFO.
Using basic tools including a plank of wood, rope, and a baseball cap fitted with a loop of wire to help them walk in a straight line, they said they made complex crop circles in England - which others then copied all over the world into the 1980s.
They made a circle for journalists, which was later declared authentic by a cereologist.
They then revealed their hoax to the world, spurring on even more copycats.
Dr Drew said there was a lot of scientific evidence to show that some crop circles were made by human time travellers or extraterrestrial beings. "Laboratory results on plant or soil samples taken from a crop circle in Brazil in October of 2016 show that it was formed by unknown sterilising images," he said.
The earliest mention of a crop circle dates back to the 1500s. A woodcut from the time showed a "mowing devil" making the pattern.
Earlier this month, US TV host Jimmy Kimmel asked former US President George Bush if he went through "secret files, the UFO documents" when he was in office.
But instead of laughing off the question, the former commander in chief replied: "Maybe."
Mr Kimmel then asked him if there were "any great secrets you know that you can't share with people?"
"Yeah, there are," Mr Bush said. "But I'm not telling you."
Many conspiracy theorists and some scientists, including Dr Drew, argued that Mr Bush's comments indicated the US government knows much more about extraterrestrial life than it has publicly revealed.
"The politicians are scared they'll lose votes if they talk about it," Dr Drew said.
He said international media had also played a part in causing the public to doubt the legitimacy of crop circles and aliens.
But according to him, its important for humans to keep seeking answers.
"The ET visitors have technologies which would benefit us greatly, for example, how to make safe, clean energy without burning oil, coal or gas," Dr Drew said.
"Ultra-fast propulsion systems, based on gravity and inertia, could carry us safely to distant planets or stars.
"We may also need to upgrade our planetary defences soon, to protect against ET's who may not be friendly."
There's still a lot more to be understood but Dr Drew's hope is that he one day gets a closer look at what was inside the UFO he believes he saw as a child.
"I'd like to meet (the extraterrestrials or human time travellers) in person," he said.
"But I don't think they're going to do that.
"Whichever scientific team is doing this I don't think we're supposed to have full knowledge of it because it will interrupt their program, whatever they're doing."