Oil giant BP will fork over the largest criminal penalty in the history of the United States and plead guilty to criminal misconduct, sources report, with more charges possibly forthcoming over the 2010 Deepwater Horizon spill in the Gulf of Mexico.

The US Justice Department admitted Thursday afternoon that two BP employees have been indicted with manslaughter for their involvement in the disaster that left 11 workers dead. Meanwhile, BP will pay the US a settlement worth $4.5 billion, including $1.3 in criminal fines, breaking the record for criminal penalties in the country previously held by drug maker Pfizer, who was penalized to the tune of $1.2 billion in 2009.

In exchange for the plea and for also admitting guilt to obstructing Congress, BP will reportedly be in the clear from any further prosecution relating to the oil spill, the sources allege. At least two BP employees might not be off the hook themselves, however, possibly facing criminal manslaughter charges for their role