Two Los Angeles County men pleaded not guilty Friday, Aug. 28, to felony robbery and grand theft charges in a debit card swap scheme targeting Wells Fargo ATMs across San Diego County.

Sergio Romero, 40, and Franklin Florez, 31, were arrested Wednesday, Aug. 26, after deputies with the San Diego County Sheriff's Office and the San Diego Fugitive Task Force located them following another suspected fraud incident in Lemon Grove, Patch reported. As we reported Friday, the cases are tied to Carlsbad Police Department investigations.

Total losses from the scheme are estimated at about $120,000, according to Fox 5 San Diego.

Authorities allege the suspects would watch victims enter their PINs at ATMs, then approach and offer assistance. During the distraction, they would secretly replace the victim's card with an identical-looking fake, according to investigators. The suspects then allegedly used the stolen cards and PINs to withdraw cash from multiple ATMs before victims realized the swap.

San Diego County Sheriff's Detective Aaron Catanach told Fox 5 San Diego the suspects sometimes waited in bank parking lots for up to 45 minutes, looking for targets.

"The majority of the victims I know about, they were over 60 years old," Catanach said.

The investigation began in May after several people reported being targeted at Wells Fargo locations in Lemon Grove. At least five victims there, including two elderly people, lost a combined $5,990, with individual losses ranging from $100 to more than $2,700, according to the Sheriff's Office.

Detectives used automated license plate readers to connect the Lemon Grove cases to about 15 additional incidents under investigation in San Diego, Chula Vista and Carlsbad. Wells Fargo also linked the men to about 15 similar crimes in Orange and Los Angeles counties. Detectives said at least one suspect may be connected to additional cases in Bakersfield and Las Vegas.

A judge ordered that the suspects' faces not be shown in media coverage of their court appearance. Romero and Florez are scheduled to return to court Thursday, Sept. 3.

Catanach urged ATM users to shield their PINs while entering them and to watch for anyone looking over their shoulder. He said people should trust their instincts if something seems suspicious.

Carlsbad residents who suspect they have been targeted can contact the Carlsbad Police Department at 442-339-2197 or San Diego County Crime Stoppers.