The last of the brothers accused of creating an infamous Mexican drug cartel pleaded guilty Friday to helping send hundreds of millions of dollars in proceeds from the United States, marking one of the final milestones in an investigation that began nearly two decades ago.

Eduardo Arellano Felix, 56, reached an agreement with prosecutors that will send him to federal prison for 15 years for conspiracy to launder money and invest funds gained from violating drug laws. He will be deported to Mexico when he completes his sentence.