SAN FRANCISCO (AP) — Patients, growers and clinics in some of the 14 states that allow medical marijuana are falling victim to robberies, home invasions, shootings and even murders at the hands of pot thieves.

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 shootout — 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 chronically 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 is difficult to get an accurate picture of crimes linked to medical marijuana because many victims don’t notify the police for fear of drawing unwanted attention to their own activities. But the California Police Chiefs Association used press clippings to compile 52 medical marijuana-related crimes — including seven homicides — from April 2008 to March 2009.

There also is plenty of anecdotal evidence:

4A man in Washington state was beaten to death last week with what is believed to be a crowbar after confronting an intruder on the rural property where he was growing cannabis to treat painful back problems.

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

— In California, a boy was shot to death in 2007 while allegedly trying to steal a cancer patient’s pot plants from his home garden.

— A respected magazine editor was killed that same year 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.

Police and marijuana opponents say the violence is further proof that the proliferation of medical marijuana carries problems that would worsen if pot is legalized or decriminalized.

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 like 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.’’

Marijuana advocates say there is adequate regulation in New Mexico, where officials say there have been no violent medical marijuana robberies.

Medical cannabis is primarily grown by a small number of regularly inspected nonprofits in New Mexico, and the state keeps their names and locations confidential. The law includes extensive requirements covering security, quality control, staff training and education about the use of the drug.

Most medical marijuana states have only vague rules for caregivers or dispensaries participating in a business with products that can fetch $600 an ounce. Some states, including California and Colorado, can only guess how many pot dispensaries they have because the businesses don’t have to register with the state.

‘‘This is ridiculous, in my opinion, to have medical marijuana and no regulation,’’ Stroup said. ‘‘A jewelry store wouldn’t open without security, and if it did, a scuzzy person’s going to break in and steal all their diamonds.’’

Stephen Gutwillig, California director of the pro-pot Drug Policy Alliance, said that while the robberies are disturbing, there is no way to conclude that legalized marijuana breeds any more crime than convenience stores, banks or homes stocked with expensive jewelry and electronics.

In fact, Denver police said the 25 robberies and burglaries targeting medical marijuana in the city in the last half of 2009 amounted to a lower crime rate than what banks or liquor stores there suffered.

‘‘I think what we are seeing is a spate of crime that reflects the novelty of medical marijuana cultivation and distribution through unregulated means,’’ Gutwillig said.

Marijuana is still illegal under federal law, but the Obama administration loosened its guidelines for prosecutions of medical pot last year. The Justice Department told federal prosecutors that targeting people who use or provide medical marijuana in strict compliance with state laws was not a good use of their time.

The decision energized the medical marijuana movement and came as Washington state and California are trying to get pot legalization measures on the ballot. Activists are still gathering signatures, and it’s not yet known if the measures will qualify for the ballot.

Meanwhile, California cities have been trying to rein in the drug in response to a medical marijuana law that is the nation’s most liberal.

Detective Robert Palacios of the Los Angeles Police Department said he has investigated a half-dozen dispensary robberies in the last year, but he has seen the number of such crimes drop in recent weeks after the City Council moved to close many stores.

In all the cases he’s investigated, armed robbers have stolen marijuana, cash and other items. They often resell the drug on the street.

‘‘They are going into a business and using a threat of force,’’ Palacios said. ‘‘Even though they are in an establishment that itself is questionably legal, it’s our duty to investigate.’’