A world-renowned slackliner who once performed with Madonna was killed in a freak BASE jumping accident in Utah over the weekend.

Andrew 'Andy' Lewis, 39, was conducting a tandem BASE jump on Sunday morning in the remote Mineral Bottom area of Grand County, near the Utah-Colorado border, when he and his 50-year-old passenger, Danny Joe Kregle, of Arizona, died, according to the Moab Times-Independent.

The accident occurred at around 8am when Lewis and Kregle jumped off a 280-foot cliff at a site known as Mary's Gash, and the parachute they shared failed to open, Hayley Ashburn, Lewis' ex-fiancé and longtime romantic partner told Outside Magazine. 

She said she spoke with Lewis's close friend Brent Cain, an EMT and firefighter who was working with Lewis on the jump and witnessed the tragedy first-hand.

Cain then had to drive out to phone emergency services as there was no cell service in the area, and first responders arrived on the scene roughly 45 minutes after Cain reached the fallen jumpers.

Both Lewis and Kregle were then pronounced dead at the scene. 

'The Grand County Sheriff's Office extends its deepest sympathies to the families, friends and all those affected by this tragic incident,' the department said in a statement. 

Lewis, who was originally from Santa Rosa, California, was well-known in the slacklining community, helping popularize 'tricklining' - performing tricks on a bouncing line - in the mid 2000s.

He clinched four straight world championships in competitive slacklining from 2008 through 2011. 

In 2011, he also set the Guinness World Record for the most side surfs on a slackline in one minute, and the following year, he performed a slackline routine during Madonna's Super Bowl XLVI halftime show.

During the performance, Lewis, dressed in a Roman toga, executed tricks on an inch-wide line while Madonna serenaded millions of viewers.

He told ABC News in the aftermath he likely would have broken his leg if he fell off the line, but insisted it was worth it for 'the moment.' 

'When you have that many people live, there's this energy that kind of gets put into you that you can't access any other way, and it's amazing,' Lewis said.

For his efforts, Madonna gave Lewis an offer to go on tour with her and perform for a mainstream audience, but he instead decided to continue slacklining and BASE jumping on his own. 

But his career was not without controversy.

In October 2013, Lewis completed what was reported as a record-length urban highline walk between the towers of the Mandalay Bay on the Las Vegas Strip, approximately 480 feet above ground level.

The following year, Lewis also made a number of illegal BASE jumps in Arches National Park and was fined $965. He was also prohibited from entering a national park for 18 months, the Times-Independent reports.

Lewis then faced controversy again in 2017, when he was charged with four misdemeanor counts of harassment after posting 'explicit and threatening' comments on Facebook after three local climbers criticized him for unlawfully decorating a local building with Christmas lights.

The City of Moab, though, dismissed the charges after Lewis pleaded no contest to a lesser charge of disorderly conduct.

By 2018, Lewis - who was widely known by the nickname 'Sketchy Andy' - founded BASE Jump Moab, a local guiding company that offered first-timers the chance to BASE jump as well as opportunities for canyoneering, rock climbing, hot air balloon rides and enjoying rope swings.

It is one of just a few companies offering the opportunity to BASE jump under Bureau of Land Management authorization in Grand County, where Moab's red rock cliffs draw BASE jumpers from around the world.

Ashburn called her late partner and friend 'an inspiration to everyone in the sport.'

'He was the pioneer of slacklining, one of the most creative and boundary breaking riggers we've ever seen,' she said. 'Andy started it all.' 

She also noted that Lewis was among the first multisport adventure athletes as a slackliner, rock climber, free soloist and BASE jumper.

Ryan Jenks, founder of gear-testing website HowNOT2, also told Outside Magazine how he became close friends with Lewis in 2016.

'Most of my best memories in life were with Andy,' he said. 

'You hear about "full of life characters," but rarely actually meet them,' Jenks continued, saying Lewis 'dove head first into life and it was chaos.

'It broke me out of my shell and gave me confidence I never had before.'

On social media, David Morrison also described Lewis as someone who did not hide from life.

'He stepped into it. Fully. Recklessly at times. Beautifully at times. But authentically.'

Morrison then went on to say Lewis leaves behind a 'myth.'

'Not a myth in the sense of something false, but in the older sense. A story that becomes larger than the individual who lived it,' he explained.

'Long after people forget dates and details, they will still tell stories about the man who walked out onto the edge, who refused the ordinary script, who treated fear almost like a conversation partner.'

Ashburn seemed to agree, saying Lewis lived and died on his own terms.

'Andy was a human being who loved to push the envelope,' she said. 'And he got away with it, spectacularly, for almost 40 years.'

Lewis leaves behind his mother, Lynn; father, Roger; and sister, Molly.