(CNN) - According his official schedule, President Obama did not attend the May 25 memorial service in Jackson, Mississippi for the workers who died in the Deepwater Horizon explosion because he was en route to a fundraiser for Sen. Barbara Boxer, D-California, in San Francisco.
At Thursday's White House briefing, Press Secretary Robert Gibbs was asked why Obama did not attend the service. The president's spokesman answered, "I'd have to look at the schedule. I don't know the answer."
CNN examined the president's schedule for that day, and according to it, the president left the White House at 2:55 p.m. EST en route to Andrews Air Force Base for the cross-country flight to the San Francisco fundraiser.
A Jackson source in possession of the memorial service program told CNN that the service began at 2:00 pm EST and lasted "more than an hour and a half" - putting the president in transit to the fundraiser during the second half of the memorial service.