A letter in Tuesday's paper echoed a theme we keep hearing since the triple homicide this month in Forestville: It was about money.

No, it was about pot.

Any other conclusion willfully ignores evidence that illicit drug-dealing is responsible for a large proportion of criminal violence in Sonoma County as well as in other North Coast counties.

Marijuana-related slayings have claimed 22 lives in four counties over the past decade. People have been killed tending marijuana fields, in drug deals that turned sour, during home-invasion robberies.

Seven killings occurred here in Sonoma County, the most recent on Feb. 5. The victims were Raleigh Butler, 24, formerly of Sebastopol, Richard Lewin, 46, of Huntington, N.Y., and Todd Klarkowski, 42, of Boulder, Colo.

We don't know how their paths crossed, but authorities say they had the same objective: to buy a large quantity of marijuana to sell on the black market. They ended up in a Forestville home where all three were shot to death. One suspect is in custody, and detectives are looking for two other "persons of interest."

It may be comforting to hold pot blameless for all this bloodshed. A less comfortable alternative is to acknowledge that demand for the drug is the first link in a chain that often ends in violence.

Another common refrain is that if pot were legal, the killing would stop.

It might end the violence, and one day marijuana may be legal. Right now, however, it isn't, not in the eyes of the federal government anyway.

California and a handful of other states allow medicinal use of marijuana. In Colorado and Washington, voters approved recreational use. Most states don't allow any use, and police may ignore users, but they pursue growers and dealers.

On a global level, Washington puts pressure on the Mexican government to crack down on cartels that smuggle marijuana into the United States.

It's the combination of demand and these legal restrictions that gives marijuana its monetary value. Take away either and the economics change.

Right now, a pound of pot sold for $1,500 in Sonoma County is worth four times as much, or more, in other states.

"If you go across time zones the price goes up significantly," a federal drug policy official told Staff Writer Julie Johnson.

Those prices draw black market growers and merchants to North Coast, but demand sets the price. Relaxing California laws further won't change that equation, and it won't address crime and violence that accompany black market marijuana operations.

We've long expressed reservations about the shadowy industry spawned by California's medical marijuana law and the wink-and-a-nod clinics selling physicians' recommendations. But we accept that marijuana has palliative properties, and California law allows users to avoid the black market by growing their own.

We also have called on Congress to clear the way for additional research of marijuana's risks and benefits. And we're listening closely to arguments in favor of legalization.

But until the hard work of changing the law is completed, you can't separate marijuana from the criminal violence that it sparks.