SAN DIEGO -- An East County man was in custody Wednesday on suspicion of carrying out a spree of robberies at San Diego dessert shops.

San Diego police arrested 24-year-old Jamel Powers at an El Cajon home on Tuesday evening, San Diego Police Department spokeswoman Monica Munoz said.

Powers, dubbed the "Ain't No Joke Bandit" by police, allegedly demanded cash from employees at ice cream and frozen-yogurt businesses in various parts of the city.

Police said Jamal Powers would pretend to be a college professor wanting to interview store managers about the business.

Once he received access to the managers, police said, Powers would tell them it was a robbery and then say, "It ain't no joke."

"Once he arrived at the restaurant and conducted an interview with the manager, he would tell them it was a robbery and that persons outside would come in if they didn't cooperate," said Sgt. Corey Chesebrough of the SDPD.

Powers is also suspected of committing four similar heists in unincorporated areas of the county, Munoz said.

Powers, an El Cajon resident, was booked on suspicion of eight counts of commercial robbery.