Condolences from allies of the movement to regulate firearms in the US poured in from across the country after it was announced that Mark Glaze, a former director at Everytown for Gun Safety and a leader in the movement, had died.

Mr Glaze was 51, and his death was ruled a suicide, a friend told The New York Times. He was incarcerated at Lackawanna County Prison in Scranton, Pennsylvania, on a driving under the influence (DUI) charge from September.

He previously joined one of Everytown’s predecessor organisations, the Michael Bloomberg-founded Mayors Against Illegal Guns, after resigning from a PR firm which contracted him to work for the group. His efforts with Mayors Against Illegal Gus was credited by many activists as part of the reason why the lobby won some victories in the wake of horrific mass shootings across the US including Newtown, Connecticut and Parkland, Florida.

Mr Glaze’s strategies were called upon by the Obama White House after the 2012 Sandy Hook shooting, though the administration’s efforts to pass bipartisan gun violence legislation ultimately failed. After Parkland, he saw greater success with a wave of boycotts aimed at the National Rifle Association (NRA), which today faces a historic anticorruption suit in New York and has filed for bankruptcy.

On Twitter, allies touted Mr Glaze’s work to fight gun violence both on the policy front and in helping grow the movement for gun control itself.

“Mark was a pioneer in the anti-gun violence movement. One of the first people I turned to after the Sandy Hook shooting. What a heartbreaking loss,” tweeted Sen Chris Murphy of Connecticut.

“You were there on Day 1 after the Sandy Hook tragedy working to end the gun violence crisis in our nation. I will never forget your words of encouragement,” added Po Murray of Newtown Action Alliance, adding: “Rest in piece, my friend.”

Shannon Watts, whose group Moms Demand Action merged with Mayors Against Illegal Guns to form Everytown for Gun Safety, wrote about how Mr Glaze helped her organisation get off the ground.

“I first met Mark Glaze in 2013, a couple of months after I’d started ⁦@MomsDemand,” she tweeted.

“As the Executive Director of Mayors Against Illegal Guns, he’d agreed to give me some money from MAIG to help us establish our grassroots,” she continued, adding: “Without Mark, there would be no Moms Demand Action, and the gun violence prevention movement wouldn’t be as strong as it is today. Mark made a real and lasting difference in the world. Now it is up to all of us to keep his goodness alive.”

The 51-year-old was awaiting trial after allegedly leaving the scene of an accident.

Before becoming “the face of the gun control movement”, per his Washington Post obituary, Mr Glaze served a number of other roles around government. He previously worked at the Campaign Legal Center, an organisation dealing with voting rights, transparency, and government ethics; he also served as an advisor to the Commission on Federal Election Reform under former President Jimmy Carter.

He is survived by one son, and numerous other family members.