In announcing the signing of Rahshead Johnson, Sarkisian said the Long Beach Cabrillo High standout could play wide receiver or defensive back.
"He is extremely competitive and displays a tremendous work ethic," Sarkisian said on USC's website.
Johnson is 5-feet-11 and 175 pounds.
He is one of several defensive backs that have signed with the Trojans, including Lamont Simmons, Jonathan Lockett and John Plattenburg.
The Trojans are also trying to sign Long Beach Poly receiver/defensive back John "Juju" Smith.