Here's why Liev Schreiber's Keppler only stuck around for four episodes of CSI's as Gil Grissom's replacement. CSI was a new kind of procedural when it debuted on CBS in 2000. The show's slick camerawork and cinematic sheen made it stand out from the TV thriller crowd, as did its focus on science and technology to solve crimes. The series also gave the underrated William Petersen - star of Manhunter and To Live And Die In L.A. - one of his best roles as crime lab supervisor Gil Grissom.
CSI seemed to be everywhere during the peak of its popularity, with Quentin Tarantino even guest-directing the season 5 finale. It later spawned spin-offs like the David Caruso-fronted CSI: Miami - which ran for ten seasons - or CSI: Cyber. The main series itself originally ended in 2015 after 15 seasons, but it was later revived in 2021 as CSI: Vegas. While the latter was intended as a one-off epilogue season, a second series was greenlit after it proved a ratings hit.
Grissom was a key component of what made CSI work, and while the show survived his original exit in season 9, his absence was missed in later series. Viewers got an early taste of a Grissom-less CSI during the seventh season when the character took a sabbatical from the Vegas lab to teach a class elsewhere. The showrunners secured a high-profile replacement in the form of Liev Schreiber as Michael Keppler, who took Gil's - who won't be back for Vegas season 2 - place during his break. Schreiber's role would prove literally short-lived, however.
Liev Schreiber's Keppler Was Always A Temporary Replacement
Keppler was a troubled character, who had previously killed the man he thought had assaulted his girlfriend, who later died by suicide. While CSI's Keppler was very good at his job, his time in Las Vegas soon came undone when he helped his late girlfriend's father Frank cover up a dual murder he committed. Frank was a corrupt cop, and in the course of covering up his crime, Keppler realizes Frank assaulted his own daughter and the man he killed to avenge her was innocent.
Liev Schreiber's time on CSI - where Taylor Swift once guest-starred - came to an end after four episodes with "Law of Gravity." This ends with Keppler confronting Frank about his actions when the latter attempts to kill a prostitute to cover up his most recent killings. Keppler ends up taking a bullet to the chest, but empties his pistol into Frank and dies himself shortly after. It was a tragic end to the character's short run, though Keppler was always intended as a brief replacement to cover Grissom's absence who - if nothing else - returning from his teaching job feeling re-energized.