The sex-trafficking trial of Sean Diddy Combs, which kicks off on Monday, marks the highest-profile case so far for a nascent group in the Manhattan U.S. Attorney's office focusing on criminal prosecution of civil rights violations.

Combs has pleaded not guilty to criminal charges that include racketeering conspiracy, sex trafficking and transportation to engage in prostitution. If convicted, he could be sentenced to life in prison.

Sean “Diddy” Combs’ prosecutors are having trouble contacting a key witness for the trial, who they now say “may not show up,” according to the New York Post. The accuser, one of five witnesses set to testify,