Key witness, Liechti, testifies in UBS tax evasion trial in Florida

FORT LAUDERDALE, Fla., Oct 23 (Reuters) - A key witness in the federal tax evasion trial of a top Swiss bank executive took the stand on Thursday to testify against his former boss, Raoul Weil, who is accused of conspiring to conceal up to $20 billion in U.S. taxpayers' assets in secret offshore accounts.