The retrial of a murder case that has transfixed Hong Kong opened Tuesday, as American expatriate Nancy Kissel again pleaded not guilty to charges that, in 2003, she bludgeoned her husband, Merrill Lynch investment banker Robert Kissel, to death after serving him a sedative-laced milkshake.

Kissel, 46, had been convicted of the murder in a 2005 jury trial and was subsequently sentenced to life in prison. But, last February, Hong Kong’s Court of Final Appeal overturned the conviction on the grounds that prosecutors had improperly cross-examined Kissel about statements she made at a pretrial bail hearing. The appellate panel also found the trial judge improperly admitted prejudicial hearsay testimony that Robert Kissel feared his wife was poisoning his whiskey.