DALLAS (December 18, 2012)—Karl G. Pratt of Granbury has been sentenced to more than four years in federal prison in a nearly $1 million investment scam involving trailer hitches.

Prosecutors Tuesday in Dallas announced the sentence for Pratt who earlier pleaded guilty to wire fraud.

Pratt was arrested last January in a scam that since 2009 drew about 50 investors to his company, Safety Sentry Inc.

Investigators say Pratt falsely claimed to have patented a device to prevent a trailer hitch from coming loose during towing.

Another claim was for a device that would deter theft of a parked and unattended trailer.

Pratt, who was also ordered to make $979,000 in restitution, didn't tell investors that his patent applications were denied.