Najib Razak, the former Malaysian prime minister who was ousted at the polls last year and now faces dozens of corruption-related charges, pleaded his case this week. But not before a judge.

Standing before a microphone in a recording studio with more than a dozen young backup singers, he delivered a baritone intro to a reworked, Malay-language version of “Kiss and Say Goodbye,” the 1970s R&B hit by the American group the Manhattans.

“This is the saddest day in my life,” Mr. Najib laments in the spoken intro, in a video posted on a Facebook page for his political party.

“On May 9, 2018, I was ousted,” he croons. “All this while I fought relentlessly for the people whom I loved and are dear to me. But what can I do?”