Stanford Political Sciences Professor Gary Cox was arrested at the Los Angeles International Airport (LAX) on May 27 for carrying an allegedly inactive grenade on a flight originating from LAX. The Los Angeles Police Department (LAPD) arrested him on the grounds of placing a destructive device in a public space after airport security agents discovered the grenade in his carry-on luggage.

Airport security called the LAPD Bomb Squad to remove and destroy the grenade. Cox was released on $500,000 bail by the LAPD that night. Cox told the Los Angeles Times that he was called by a police officer last Friday, and was informed that the charges had been dropped.

He attributed the incident to an honest mistake. Cox explained that he was in Los Angeles to make arrangements for his childhood home after both his parents passed away earlier this year. The grenade, a U.S. Army MK2, used to belong to Cox’s father, who was a captain in the United States Navy during World War II, serving in the Pacific. According to Cox, his father used the grenade as a paperweight.

Cox told the Los Angeles Times that he attempted to bring the grenade to his son as an heirloom, and had not thought about the paperweight as a grenade when he packed it in his carry-on luggage.