After initially being stationed at Ft. Bragg, (now Ft. Liberty) NC, Greg later became an army CID agent (Criminal Investigator) while assigned as a Military Police Investigator in Darmstadt, Germany. When his Germany tour ended in 1977, he was appointed to Warrant Officer at his next duty station, which was Fort Ord, California. He left active duty in 1980 as a Chief Warrant Officer 2, and became a police officer in Salinas, California, which is in Monterey County. However, he remained in the Army Reserves. He completed a total of 40-years of active duty and reserve service, retiring in 2012 as a Chief Warrant Officer 5.
Greg left the Salinas Police Department in 1981 and transferred to the Pasadena PD when his wife, Virginia, had a job offer in Los Angeles. In December of 1983, he accepted a special agent position with the Drug Enforcement Administration (DEA) and served in Los Angeles, Monterey, California, DEA Office of Training at the FBI Academy, Quantico, Virginia, Islamabad, Pakistan and was the Resident Agent in Charge of DEA's Karachi, Pakistan office. Greg was then transferred back to DEA's Los Angeles Division where he was a group supervisor at the the Orange County resident office. He later was brought back to the L.A. office to serve as the Organized Crime Drug Enforcement Task Forces coordinator. He retired from DEA in December, 2003. While in Islamabad, Greg was a member of the team that captured Ramzi Yousef, the mastermind of the 1993 New York City World Trade Center bombing. Yousef was the world's most wanted terrorist at the time. Greg collected critical evidence of Yousef's planning the Bojinka Files terrorist plot in which Yousef and others conspired to plant bombs on, and simultaneously blow up, 12 U.S. domestic airliners over the Pacific Ocean. Greg testified at his trial in which Yousef represented himself. Between his careers as a DEA/CID agent, he traveled to over 60-countries on investigations, training assignments, and personal travel.