There have been dozens of cases in recent months alone. The issue received more attention this week after a prominent medical-marijuana activist in Seattle nearly killed a robber in a shoot-out - the eighth time thieves had targeted his pot-growing operation.

Critics say the heists and holdups prove that marijuana and crime are inseparable, though marijuana advocates contend that further legalization is the answer. News of crimes related to medical marijuana comes at an awkward time for California and Washington advocates who are pushing to pass ballot measures to allow all adults, not just the seriously ill, to possess the drug.

"Whenever you are dealing with drugs and money, there is going to be crime. If people think otherwise, they are very naive," said Scott Kirkland, the police chief in El Cerrito, Calif., and a vocal critic of his state's voter-approved medical-marijuana law.

"People think if we decriminalize it, the Mexican cartels and Asian gangs are going to walk away. That's not the world I live in," Kirkland said.

Activists and law enforcement officials say it's hard to get an accurate picture of crimes linked to medical marijuana because many drug users don't report the crimes to police for fear of arousing unwanted attention from the authorities. But the California Police Chiefs Association used press clippings to compile 52 crimes related to medical marijuana - including seven homicides - from April 2008 to March 2009.

There also is plenty of anecdotal evidence:

Medical marijuana activist Steve Sarich exchanged gunfire with intruders in his Seattle home Monday, shooting and critically injuring one of them.

A respected magazine editor was killed in 2007 by robbers who targeted his Northern California home for marijuana and money after hearing that his teenage son was growing pot with a doctor's approval.

Robbers killed a security guard at a Los Angeles medical-marijuana dispensary in 2008. Pot activists say the opposite: that prohibition breeds crime, and legalization would solve the problem. They also say the robberies have exposed the need for more regulation of medical-marijuana laws in states such as California, Washington, and Colorado.

"The potential for people to get ripped off and for people to use guns to have to defend themselves against robbers is very real," said Keith Stroup, founder and chief legal counsel for the National Organization for the Reform of Marijuana Laws. "But it's nothing to do with medical marijuana. It is to do with the failure of states to regulate this."

Advocates say there is adequate regulation in New Mexico, where officials say no violent medical-marijuana robberies have occurred.