Eraser (1996)

Federal Marshal John Kruger (Arnold Schwarzenegger), is a member of an elite group within WITSEC that erases the identities of witnesses whose proposed testimony puts their lives in danger.

Now he faces his greatest challenge, protecting his witnesses from someone inside whose knowledge and training are a match for his own. Kruger himself falls under suspicion as the traitor and he sets out to prove his innocence to Samaritan (James Caan), his former mentor, and Beller (James Coburn), the head of the program. He soon finds himself on the run to save the one woman who holds the key to the truth.