A retired Cincinnati police captain will be among the speakers Thursday at a local event about legalizing the medicinal use of marijuana in Ohio.   Howard Rahtz, who retired from the Cincinnati Police Department in 2007, will speak at a forum organized by the Ohio Medical Cannabis Association (OMCA). The group is trying to collect enough signatures to get an amendment to Ohio’s constitution on the ballot that would allow the use of cannabis with a physician’s prescription.   The event will begin at 6:30 p.m. in Room 500 at Swift Hall on the University of Cincinnati campus.   Other speakers will include Theresa Daniello, a mother of five children who is OMCA’s executive director, and Mark Ramach, the group’s attorney.   After their presentation, attendees can participate in a question and answer session about the proposed amendment.   Rahtz, who is a volunteer with Law Enforcement Against Prohibition, is a conservative who has no interest in using drugs but supports legal and controlled public sale of marijuana. With a dual background in drug treatment and drug interdiction, Rahtz has first-hand experience with drug enforcement policy.   “I defy you to find anybody who will applaud what the war on drugs has accomplished,” Rahtz told CityBeat in June 2011. “Use rates have not changed in four decades. We’ve accomplished nothing. We spend more money, we incarcerate more people than any other place in the world and we end up with less for it. The fact is, what we’re doing isn’t working. My question is, particularly in this age of shrinking resources, are we going to continue pouring money down this rat hole?”