Mark Allen Hopkinson was born on October 8, 1949, in Evanston, Wyoming. He grew up in the Bridger Valley area, where his family had a ranching and construction business. Mark was active in sports during his youth and even received a football scholarship to attend the University of Arizona.

However, his life took a different turn when he faced legal troubles. In 1971, while he was away at college, he was convicted for delivering controlled substances, which led to a federal prison sentence. After his release, Mark returned to Wyoming around 1975.

Once back home, he became involved in several legal disputes. One notable conflict was between his family and another family over water rights, which escalated into a lawsuit. Mark sought to overturn a judgment against his family in this case. During this period, he also had a falling out with Vincent Vehar, an attorney involved in the legal disputes concerning his trailer court development. By 1976, Mark was also known to have hired others for various jobs, indicating a network of associates who engaged in criminal activities.

Mark Allen Hopkinson was convicted for the murders of Vincent Vehar, Beverly Vehar, John Vehar, and Jeffrey Green. In 1977, he plotted the bombing of the Vehar family home. He hired Michael Hickey to carry out the attack, which resulted in the deaths of Vincent, Beverly, and their son John. Another son, Tony Vehar, survived the explosion. Hickey executed the bombing on August 7, 1977, shortly before Hopkinson was scheduled to be deposed for a lawsuit regarding a sewer connection involving the Vehars.

In 1979, Hopkinson was tried for these murders. His co-conspirator, Jeff Green, who was involved in previous and subsequent criminal activities, played a significant role in the case. After initially testifying against Hopkinson, Green later recanted his statement, fearing for his life. However, he was murdered in May 1979, shortly before a grand jury was to convene regarding the Vehar bombing. His body was found with signs of torture and multiple gunshot wounds.

Hopkinson was arrested and tried, where a jury found him guilty. He was sentenced to life imprisonment for the murders of the Vehars and received a death sentence for the murder of Green. Although he maintained his innocence throughout, he was executed by lethal injection on January 22, 1992. He was pronounced dead shortly after midnight, making him the first person executed in Wyoming since 1965. His last meal included pizza and a fruit plate, shared with family members, and he expressed his belief in his innocence up until the end.