Updated

WASHINGTON (AP) — A Senate panel is taking a closer look at the oil rig explosion in the Gulf of Mexico that resulted in a spreading oil slick of millions of gallons of crude oil.

Senate Energy and Natural Resources Committee Chairman Jeff Bingaman, a New Mexico Democrat, says he hopes to determine "the cascade of failures that caused the catastrophic blowout" on April 20.

Interior Secretary Ken Salazar is the leadoff witness. He was to be followed by other federal officials.