No charges have been filed against Walker.
The Rams do not publicly comment on players they release, but a source told ESPN's Alden Gonzalez that Walker was let go largely because they did not see a place for him on their roster.
According to a report by the Baton Rouge Advocate, Lafayette authorities are wrapping up an investigation into claims of sexual assault lodged by two women against Walker and an acquaintance on the night of Feb. 28.
Walker's agent declined to comment, and no attorney statements have been made on his behalf.
Walker, 27, is from nearby New Iberia, Louisiana, and began his career with the New Orleans Saints from 2012 to 2014. He then spent two years with the Detroit Lions before signing a one-year veteran-minimum contract with the Rams in March.
He went to the Rams as a backup for Michael Brockers and Aaron Donald, and wasn't expected to receive much playing time because the team has a lot of depth on its defensive line. Walker's dead cap hit is $80,000.
Lafayette Parish District Attorney Keith Stutes told The Advocate that detectives forwarded their investigative findings to his office June 15. He said, "It's presently being reviewed," and it is too soon to say whether he will present the evidence to a grand jury.
According to The Advocate, investigators declined to discuss the inquiry, but they did release a bare-bones initial report that confirmed the existence of the probe without naming any suspects.
The Advocate also obtained a civil court filing that accused Walker and acquaintance Justin Williams of forcing the women into sexual acts after taking them from a nightclub to a hotel, and possibly drugging them at the nightclub. A restraining order was granted against Williams, and another was requested against Walker.
ESPN's Alden Gonzalez contributed to this report.