Next-door neighbor Kayla Latch, 18, lives with her mother and her two brothers and said they were worried that toxic chemicals could be released when investigators enter the home.
Latch said Curtis lived with a woman and teenage boy when he first moved in, but they appeared to have moved out.
Kayla Latch said she slept in the living room Wednesday night.
"I'm still a little scared because my room is right next to his house," Latch said. "I didn't even sleep in my bed."
Latch's mother, Melissa Strickland, two men who identified themselves as being with the FBI came to her house Thursday and asked about the man next door. She said they never identified Curtis by name.
"They asked me if I saw a lot of people coming and going from his house," she said. "I told them, "No."
Ricky Curtis, who said he was Kevin Curtis' cousin, said the family was shocked by the news of the arrest. He described his cousin as a "super entertainer" who impersonated Elvis and numerous other singers.
"We're all in shock. I don't think anybody had a clue that this kind of stuff was weighing on his mind," Ricky Curtis said in a telephone interview.
Ricky Curtis said his cousin had written about problems he had with a cleaning business and that he felt the government had not treated him well, but he said nobody in the family would have expected this. He said the writings were titled, "Missing Pieces."
A MySpace page for a cleaning company called The Cleaning Crew confirms that they "do windows" and has profile photo of "Kevin Curtis, Master of Impressions." A YouTube channel under the name of Kevin Curtis has dozens of videos of him performing as different famous musicians, including Elvis Presley, Buddy Holly and Kid Rock.