AURORA | A year after a guard was shot dead at an Aurora marijuana store, his killers are still unknown and little has changed in the recreational marijuana industry.

Despite a massive reward that has climbed to $50,000, in addition to pleas from the slain guard’s loved ones for information about the murder, police  are continuing to search for leads.

Travis Mason, 24, was working at the Green Heart Marijuana Dispensary, 19005 E. Quincy Ave. in Aurora, when he was fatally shot at at about 9:44 p.m. on June 18.

Police found Mason after being called to the store on a report of a robbery and shots fired.

Mason was taken to a nearby hospital where he was later pronounced dead. The Arapahoe County Coroner’s Office said Mason was shot three times, including once in the head.

Police last year released surveillance images of the two gunman and described the pair as black males with handguns.

Aurora police spokesman Sgt. Chris Amsler said this week that police don’t have any additional information to release about the suspects.

Police offered a $30,000 reward for information on Mason’s slaying last year, but Amsler said this week the reward has now been upped to $50,000.

Several companies and organizations have contributed to the reward, including Denver Metro Crime Stoppers, Shortline Automotive Group, Euflora, a neighboring dispensary, the federal bureau of Alcohol, Tobacco and Firearms, and the Aurora Police Reward Fund.

After Mason’s slaying, marijuana industry leaders said it shined a light on an issue that has bedeviled marijuana retailers since legal weed sales started: Shops don’t have much access to banks because marijuana remains illegal under federal law, so the businesses generally operate cash-only. And those large sums of cash on hand make the stores inviting spots for thieves.

U.S. Rep. Ed Perlmutter (D-Golden) cited Mason’s murder earlier this year when he introduced the Secure and Fair Enforcement Banking Act, which would protect financial institutions serving marijuana businesses from federal government reprisal.

“With the majority of states now allowing for some form of recreational or medical marijuana, we have reached a tipping point on this issue and it’s time for Congress to act,” Perlmutter said in a statement after introducing the bill. “Allowing tightly regulated marijuana businesses the ability to access the banking system will help reduce the threat of crime, robbery and assault in our communities and keep the cash out of cartels.”

That bill was referred to the House Judiciary in late April where it has sat since. Similar bills have been introduced before — including one by Senators Michael Bennet and Cory Gardner in 2015 — but have also failed to pass.

Local pot retailers say that while they don’t have the stacks of cash on hand that they did in the very early days of the industry, they still have to take security measures that look more like what a bank would use than a typical retail storefront.

Aurora police ask anyone with information about the incident to call Agent Matthew Ingui with the Major Crimes/Homicide Unit at 303-739-6067. Tipsters can also call Metro Denver Crime Stoppers at 720-913-7867. Those who call Crime Stoppers can remain anonymous and be eligible for a reward.