Dana Savorelli, owner of the sanctuary often known as Monkey Island, is seeking monetary and punitive damages from defendant Catherine Montes, who was once a volunteer at the sanctuary, The Kansas City (Mo.) Star reported.
Montes, however, has denied that she took the monkeys and is in turn suing Savorelli for actual and punitive damages, whom she says has misrepresented the case to police and reporters.
The suits stem from the October 2007 disappearance of the three monkeys from the sanctuary in Greenwood.
Montes was a prime suspect at the time, but charges against her were dropped in 2008, a month after two of the monkeys were recovered, because of problems with evidence, Jackson County prosecutors said at the time.
The trial has been unusual, as Savorelli held a 3-month old white-headed gibbon ape as he testified Tuesday.
The case is scheduled to continue today.