A lawyer representing multiple law enforcement whistleblowers in Arkansas discovered surveillance malware after receiving an external hard drive from his clients' department.

After requesting internal emails for the case, North Little Rock lawyer Matthew Campbell became suspicious when the Fort Smith Police Department decided to place the files on a hard drive and send them through Federal Express.

Campbell, who normally receives files via email, told the Northwest Arkansas Democrat Gazette that the department's decision immediately raised red flags.

"Something didn't add up in the way they approached it, so I sent it to my software guy first," Campbell said. "I thought 'I'm not plugging that into my computer,' so I sent it to [a software expert] to inspect."

After carefully inspecting the hard drive, security consultant Geoff Mueller discovered well known malware, capable of implanting backdoors and logging passwords.