Peter Carlson in Smithsonian Magazine:
Elvis was traveling with some guns and his collection of police badges, and he decided that what he really wanted was a badge from the federal Bureau of Narcotics and Dangerous Drugs back in Washington. “The narc badge represented some kind of ultimate power to him,” Priscilla Presley would write in her memoir, Elvis and Me. “With the federal narcotics badge, he [believed he] could legally enter any country both wearing guns and carrying any drugs he wished.”
After just one day in Los Angeles, Elvis asked Schilling to fly with him back to the capital. “He didn't say why,” Schilling recalls, “but I thought the badge might be part of the reason.”
On the red-eye to Washington, Elvis scribbled a letter to President Nixon. “Sir, I can and will be of any service that I can to help the country out,” he wrote. All he wanted in return was a federal agent's badge. “I would love to meet you,” he added, informing Nixon that he'd be staying at the Washington Hotel under the alias Jon Burrows. “I will be here for as long as it takes to get the credentials of a federal agent.”
After they landed, Elvis and Schilling took a limo to the White House, and Elvis dropped off his letter at an entrance gate at about 6:30 a.m. Once they checked in at their hotel, Elvis left for the offices of the Bureau of Narcotics and Dangerous Drugs. He got a meeting with a deputy director, but not approval for a bureau badge.
More here.