The number of violent armed robberies at legal marijuana businesses around the country is staggering.

Who will protect the individual businesses that are in the legal medical and recreational marijuana industry in Massachusetts? The problem isn’t marijuana driven, it’s not “reefer madness” that is the cause of crime. The cause is the same as any robbery – greed and the willingness of bandits to use violence to obtain wealth.

CNBC news took a look at the problem a few years ago when Colorado legalized recreational pot. "Everyone in the industry is having nightmares," says Michael Elliot, executive director of the Marijuana Industry Group, a powerful young lobby in Colorado. "You hit a 7-Eleven, you'll get 20 bucks. You hit a dispensary, you'll get $300,000 on a good day," adds Mitch Morrissey, District Attorney for Denver. "It's only a matter of time before someone gets shot."

According to CNBC, about 50% of the marijuana businesses have been robbed in Colorado. Some of the robberies are simple burglaries, but others involve armed gangs assaulting employees and even kidnappings.

Colorado isn’t the only state with legal marijuana and it isn’t the only state with a related violent crime. The investigation by CNBC says “The worst violence has been in California, where in 2010 a gunman forced workers down on the ground, robbed their medical marijuana dispensary, and returned moments later to shoot both in the back of the head. But the fate that's really spreading terror in Colorado fell just shy of murder.”

“It began when three men broke into the home of a dispensary owner in Newport Beach, Calif., according to police reports that surfaced last fall. They zip-tied the man, dragged him into a van, burned him with a blow-torch, doused him in bleach, severed his penis, and then drove away with it—all in a bid to learn where he was hiding his cash.”

The violence in other states should serve as a warning to Massachusetts and guide policy to protect the employees and property of the industry.

Chris McCarthy is the host of The Chris McCarthy Show on 1420 WBSM New Bedford. He can be heard weekdays from 10 a.m. to noon. The opinions expressed in this commentary are solely those of the author.