8:07pm: Olivo's deal with the Marlins is worth $800K, reports Juan C. Rodriguez of the South Florida Sun Sentinel (on Twitter). The Marlins can release him within 45 days without owing him the rest of that amount, however.
MLB.com's Joe Frisaro had previously reported that Olivo was "a strong candidate to return" to the Marlins. Frisaro also said "there are indictations [Olivo] will wind up" with his former team.
After deciding to use Devin Mesoraco as Ryan Hanigan's backup, the Reds offered the mandated $100K retention bonus for Olivo to head to Triple-A. Olivo declined and became a free agent. As Frisaro notes, Jeff Mathis' broken collarbone leaves the Marlins without an experienced catcher, aside from Koyie Hill.
Olivo, 34, hit .222/.239/.381 in 323 plate appearances for the Mariners last year. He was with the Marlins from 2006-07, hitting 32 home runs in 249 games. Olivo ranks fourth among active catchers with 141 career home runs.
Charlie Wilmoth contributed to this post.