A staunch supporter of the rights of immigrants - and a married father of five - was killed last week when an illegal immigrant from El Salvador facing deportation crashed into his motorcycle in Colorado.

Sean Buchanan, 45, was driving northbound on Highway 83 on August 2 when Colorado State Patrol say a southbound truck operated by Miguel Ramirez Valiente went off the side of the road, then over-corrected into the wrong lane and crashed into Buchanan's bike, killing him.

Valiente, an undocumented immigrant who was slated for deportation eight months earlier, was charged with misdemeanor careless driving with a revoked license in the deadly accident.

In an ironic twist, Buchanan was known among friends a passionate advocate for all immigrants.

Sean Buchanan, 45 (left), a father-of-five from Colorado and an immigration advocate, was killed when illegal immigrant Miguel Ramirez Valiente (right) crashed into his motorcycle

Buchanan leaves behind his wife of 16 years, author Kathy Wierenge Buchanan, and their five children between the ages of 6 and 15 (pictured together)

Officials do not suspect that drugs, alcohol or excessive speed played a role in the collision, reported The Colorado Springs Gazette.

Valiente has a criminal record in Colorado that includes a 2018 conviction for a DUI charge, which earned him a year's probation and the revocation of his license, and a guilty plea to a charge of reckless endangerment in a child neglect case.

On August 1, less than 24 hours before the deadly crash that killed Buchanan, Valiente's probation was extended because he had failed to complete his court-ordered treatment program and community service.

He made national headlines in January when he sought sanctuary at All Souls Unitarian Universalist Church in January to avoid deportation to El Salvador during the federal government shutdown.

'I can’t be separated from them,' he said at a press conference at the time, according to The Denver Channel. 'I have always worked hard to support my family, and they depend on me.'

The family had bought a new home in Castle Rock, Colorado, and were in the process of moving there form Colorado Springs

The Buchanans adopted two boys, Michel and Divin, from Burundi in Africa

Sean had just started a new job in communications. His wife is the author of The Brio series of books for teenage girls, and a writer and director for an Evangelical Christian radio show

But according to a close acquaintance of Valiente's speaking to The Denver Channel on condition of anonymity, the reality of his life was far from the public image he had sought to create.

'This family deserves to know who they’re dealing with,' she said. 'He's an alcoholic and an abuser.'

The woman argued that the fatal accident that took Buchanan's life could have been prevented, especially given Valiente's history of run-ins with the law.

'My personal opinion is that we don’t do enough to stop this kind of thing because it could have been stopped,' she said. 'You’re here and you’re a hard worker and you’re not causing trouble and doing bad things, that’s fine, but he had already been in trouble, several times, and now we have a death because of it.'

Buchanan had just started a new job in communications. His wife of 16 years, Kathy Wierenga Buchanan, is the author of The Brio series of books for teenage girls, and a writer and director for Adventures in Odyssey, an Evangelical Christian radio show produced by the conservative organization Focus on the Family.

The Buchanans have five children: daughters Jasyln, 15, Maleah, 12 and Bella, 10, and two sons they adopted from Burundi, eight-year-old Michla and six-year-old Divin.

Valiente (pictured with his family) made national headlines in January when he sought sanctuary at All Souls Unitarian Universalist Church in January to avoid deportation to El Salvador

The family were in the process of moving from Colorado Springs to Castle Rock, where they had bought a new home to 'start a new chapter of their life,' according the description of a GoFundMe campaign launched by a friend in the wake of Buchanan's death.

As of Friday morning, the online fundraiser organized for the Buchanan family has drawn more than $72,000.

Valiente has a criminal record in Colorado that includes a 2018 conviction for a DUI charge and a guilty plea to a charge of reckless endangerment

On the morning of the crash, Sean and Kathy were planning to go for a drive to the new house together, by at the last moment he decided to drop off his motorcycle at in preparation for the big move.

So he and his wife split, up, with Sean driving his bike on Highway 83 and Kathy taking Interstate 25. They were supposed to meet up at their new address in Castle Rock and later return to Colorado Springs together, but Sean never made it.

Kathy said as she was driving, she saw emergency vehicle lights, an overturned truck and her husband's bike.

The tragic irony of what happened is not lost on those who knew Sean Buchanan and his pro-immigration stance.

'Sean was an advocate for people who were trying to get into our country. He was a huge advocate,' family friend Amy Savage said. 'He just was a man who loved and accepted everyone.'

In a Facebook status update announcing a celebration of life service for her late husband, his wife Kathy asked people to donate to Casa de Paz, an organization in Aurora that provides shelter, meals, access to phones and transportation to families separated by immigrant detention.