UBS AG's $1.5 billion fine for rigging global interest rates expands the scandal to include bribery and highlights the influence of a trader in Tokyo who colluded with other banks to align their submissions.

The employee led efforts to influence Japanese Yen Libor submissions by paying brokers as much as 15,000 pounds ($24,400) a quarter and offering a payment to another for helping him keep that day's rate low. The banker, identified by regulators as Trader A, worked at UBS in Tokyo from 2006 to 2009 and directly contacted employees at other banks to influence their submissions at least 80 times.

"I need you to keep it as low as possible," Trader A wrote to the broker on Sept. 18, 2008, referring to six-month yen Libor. "If you do that … I'll pay you, you know, $50,000, $100,000… whatever you want … I'm a man of my word," according to transcripts released by the U.K. Financial Services Authority today.