The 6-foot-1 Kaesviharn has played in 42 games for the Bengals the past three seasons, starting 16 of them. His career totals include 145 tackles and six interceptions.
Kaesviharn played every game last season, switching between the two positions, and had 59 tackles, a sack and an interception. He was primarily a cornerback the previous two seasons, making three interceptions in 2001 and two in 2002.
"Kevin is a versatile player who gives us options because of his ability to play safety or cornerback," said defensive coordinator Leslie Frazier. "Last year was his first year with safety as his primary position, and I expect him to take giant steps this year, building on the year's experience he had."