Detection of cocaine and metabolites from mouse femur buried in soil

•Cocaine shows higher concentrations in femur than in heart blood or femoral muscle.•Cocaine is detectable in bone for up to 180 days after burial.•Partition coefficient is important indicator in drug extraction from bone samples.•Drug used at the time of death can be detected by drug analysis from a bone. Drug addicts are frequently involved in committing homicides, and burial in the ground is often performed by offenders for body disposal. Therefore, toxicological analyses of buried bones are vitally important for investigating the cause and circumstance of death. Cocaine concentrations in heart blood, femoral muscle, and femur were measured in mice after injections of 5, 15, and 30 mg/kg cocaine and in femurs buried in soil. The concentrations of cocaine in femurs (253.67–1345.31 ng/g) were higher than those found in heart blood (3.14–28.73 ng/mL) and femoral muscle (76.41–429.76 ng/g). The cocaine concentrations in buried femurs (54.83–388.68 ng/g) were significantly lower than those in unburied femurs (253.67–1345.31 ng/g). Further, cocaine was detected in femurs after being buried for 7–180 days in soil. These findings indicate that cocaine concentrations are higher in bone than in heart blood and femoral muscle and that the concentration decreases after burial in soil.