Federal prosecutors today announced that all of the Colorado medical-marijuana dispensaries targeted for operating near schools have halted marijuana sales as demanded.

Prosecutors sent the letters to certain dispensaries within 1,000 feet of schools last month, warning them to close or face criminal or civil punishment. It was the most aggressive action yet by federal authorities against businesses that are legal under state law but illegal under federal law.

Letters went to 23 dispensaries and to their landlords. Owners of 22 dispensaries have since decided to shutter those targeted locations — either moving or closing for good. A letter to one dispensary was rescinded after it was determined that the school

Indispensary employee Brian Balliett reaches into the near-empty shelves of the Indispensary"s Bijou Street medical marijuana dispensary Sunday evening, February 26, 2012. The dispensary closed its doors Sunday amid a federal threat of criminal prosecution or seizure. (GAZETTE | Mark Reis)
building nearby was not currently being used to educate children, the U.S. Attorney's office said in an announcement.

Drug Enforcement Administration agents checked every dispensary for compliance with the letters. According to the announcement, agents entered five stores after being unable to tell whether the stores were closed. They determined those businesses had stopped selling marijuana.

"The closure of the targeted dispensaries today," new Colorado DEA Special Agent in Charge Barbra M. Roach said in a statement, "will make those affected schools more secure for our children and teachers throughout the State of Colorado."

Colorado U.S. Attorney John Walsh has said he wants to remove dispensaries from around schools because he is worried about increased youth use of marijuana and the impact the businesses have on kids' attitudes toward the drug. Federal law contains enhanced penalties for people who sell drugs within 1,000 feet of a school.

"These stores were closed without incident," Walsh said in a statement. "This effort is about protecting children from illegal drugs, and maintaining drug free zones around our schools in compliance with federal law."

Prosecutors intend to send letters to more dispensaries that are within 1,000 feet of a school "soon," according to today's announcement.

John Ingold: 303-954-1068 or jingold@denverpost.com