Court papers show Ms. Lee has received immunity from prosecutors in exchange for her testimony as a witness at next week's trial of former campaign treasurer Jia "Jenny" Hou and fundraiser Xing Wu "Oliver" Pan.

WSJ: Trial Pits Liu's Aide, Ex-Backers

Liu's ex-campaign treasurer, Jia "Jenny" Hou, and former Liu fundraiser Xing "Oliver" Wu Pan are facing federal charges of conspiring to break campaign finance laws.

WSJ: Trial opens for aides of NYC mayoral hopeful

On Thursday, Ms. Lee testified for a second day in Manhattan federal court at the trial of Jia "Jenny" Hou, Mr. Liu's former campaign treasurer, and Xing Wu "Oliver" Pan, a longtime campaign contributor.

WSJ: City Comptroller John Liu Stands By His Aide