A Beech Grove man will serve a year behind bars for planting a bomb in the truck of an undercover agent who was going to testify against him in a drug case.The man, Robert Lee Garrison, 41, entered guilty pleas before Circuit Court Judge Bart Stanley to charges of possession of an explosive device, fabricating evidence, and delivery of drugs. He was ordered to serve one year of an 11-year sentence. The remainder of his term will be spent on probation.His jail time comes after he placed two pipe bombs, along with meth lab components, in the vehicle of two drug informants who had helped bring about his indictment on narcotics charges.