The Deepwater Horizon blowout preventer is lifted out of the Gulf of Mexico by the Helix Q4000 near the coast of Louisiana, Saturday, Sept. 4, 2010. (AP Photo/Patrick Semansky)

The blowout preventer has been recovered so that investigators can get to the bottom of what caused the worst oil spill ever.

WBZ’s Ed Walsh talks about it with ABC’s Matt Gutman.