June 28 (UPI) -- Florida police put an innocent man in jail for three months after they mistook drywall powder for cocaine powder.
Karlos Cashe was pulled over by Oviedo, Fla., police in March for a traffic infraction. But the police officer saw white powder around the floorboard area and suspected it of being cocaine.
Cashe, who is a handyman, explained that the white powder was drywall powder, which probably got on his clothes when he was working and fell onto the floorboard.
However, the officer conducted a "field test" of the powder and it tested positive as cocaine.
"I know for a fact [that] it's drywall because I'm a handyman," Cashe told WFTV. "I said that continuously during the arrest stop.
Cashe, who was on probation for marijuana and cocaine charges stemming from 2015, was arrested for cocaine possession and placed in jail until lab tests of the disputed substance were done. He was ineligible for bail because he was on probation.
It took 90 days for the lab results to be completed and Cashe was proven right: The substance was, indeed, drywall powder.
"I sat there 90 days knowing I was innocent," Cashe said.
Roadside field tests have been criticized for their inaccuracy.
For example, some field tests use a chemical called cobalt thiocyanate that turns blue when it comes in contact with cocaine. But the chemical also turns blue when exposed to about 80 other compounds, including acne medication, household cleaners, and other legal, everyday substances, according to a ProPublica investigation on the inaccuracy of the roadside field tests.
In some cases, the roadside drug tests compel a person to plead guilty for drug possession even when they're innocent.
In 2016, the Houston Chronicle found 298 cases between 2004 and 2014 in which a person pleaded guilty for possession after a roadside test came up with a false positive.