The signs: Increased business at rehab centers. Those Ski-related personal ads. A big spike in death rates. The trend began to reveal itself about five years ago — in centrifuges and under microscopes — at the University of Florida’s Forensic Toxicology Laboratory. Each year, the lab assists seven Florida medical examiners’ offices with about 3,000 cases, helping to identify toxic substances in bodies as medical examiners perform autopsies. Dr. Bruce Goldberger, the UF toxicologist who runs the lab, says he began to notice a “significant increase” in the number of cases in which cocaine either caused the death or was present in the blood stream. When he and his colleagues looked at data collected by the Florida Department of Law Enforcement from all 24 of the state’s medical examiners, they found that cocaine-related deaths had been rising all over Florida — from 1,034 in 2000 to 2,052 in 2006. The raw numbers also translated into a statistical spike in the cocaine-related death rate, from 6.4 deaths per 100,000 people in 2001 to 11.2 in 2005.