MIAMI (AP) — A former career U.S. diplomat was sentenced Friday to 15 years in federal prison after admitting he worked for decades as a secret agent for communist Cuba, a plea agreement that leaves many unanswered questions about a betrayal that stunned the U.S. foreign service.

Manuel Rocha, 73, will also pay a $500,000 fine and cooperate with authorities after pleading guilty to conspiring to act as an agent of a foreign government. In exchange, prosecutors dismissed more than a dozen other counts, including wire fraud and making false statements.

“Your actions were a direct attack to our democracy and the safety of our citizens,” U.S. District Court Judge Beth Bloom told Rocha.

Rocha, dressed in a beige jail uniform, asked his friends and family for forgiveness. “I take full responsibility and accept the penalty,” he said.

The sentencing capped an exceptionally swift criminal case and averted a trial that would have shed new light on what, exactly, Rocha did to help Cuba even as he worked for two decades for the U.S. State Department.