An Arkansas lawyer currently involved in a police whistleblower case was in for a rude surprise when he received an external hard drive via Federal Express from a law enforcement attorney: It was stuffed with three different kinds of surveillance malware.

Lawyer Matthew Campbell of North Little Rock first started thinking something was wrong when the attorney for the Fort Smith Police Department responded to his request for evidence by sending him a hard drive. Typically, Campbell had received evidence via email, the US Postal Service or a cloud-based storage system.

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

After the security consultant took a look at the hardware, he found it was set up to intercept Campbell’s passwords, take over control of his computer and allow for the installation of additional malware. The presence of this software wasn’t an accident, according to an affidavit on the case filed last week.

“The placement of these trojans, all in the same sub-folder and not in the root directory, means that [t]he trojans were not already on the external hard drive that was sent to Mr. Campbell, and were more likely placed in that folder intentionally with the goal of taking command of Mr. Campbell's computer while also stealing passwords to his accounts,” reads the affidavit, as quoted by Ars Technica.

Lawyer representing whistleblowers finds malware on drive supplied by cops: http://t.co/8KgESrY8tg — Runa A. Sandvik (@runasand) April 14, 2015

As a result, Campbell has asked the court to hold the defendants in the case in contempt. He is also prepared to file a lawsuit regarding the malware incident.

The case involves three police officers – Don Paul Bales, Rick Entmeier and Wendall Sampson Jr. – who tried to blow the whistle on officials for wrongful behavior. Bales was ultimately fired.

Campbell claims the plaintiffs were subject to several investigations for trying to report unlawful practices – such as when one officer’s wife, a civilian employee at the department, illegally obtained overtime pay, the Gazette reported. In another case, Fort Smith Police Chief Kevin Lindsey was allegedly “misled” into firing a probationary officer.

On Monday, Lindsey told the Gazette there was no comment on the pending litigation.

"We're going to let the courts speak on that when the time comes," Lindsey said. "We'll let the courts get this worked out and let the disposition speak for itself."