An attorney appointed to represent 39-year-old Kenneth Manzanares, accused of killing his wife aboard a cruise ship traveling along Southeast Alaska in July, entered a "not guilty" plea on his behalf Wednesday.

In his second federal court appearance in Anchorage via video conference from Juneau, Manzanares sat quietly in a yellow jumpsuit, answering only a few yes-or-no questions from the judge.

Since his initial appearance on July 27, a grand jury in U.S. District Court for the District of Alaska indicted him on a first-degree murder charge. 

Manzanares' wife, Kristy Manzanares, was found dead July 25 in a blood-splattered cabin aboard Princess Cruises' Emerald Princess, which diverted to Alaska's capital city for the investigation. Federal authorities have led the investigation because the death occurred in U.S. waters.

According to charging documents in the case, Manzanares told a witness he killed his wife because "she would not stop laughing at me."

A witness also told authorities he saw Manzanares drag his wife towards the balcony. The witness then said he grabbed the ankles of the woman's body and pulled her back into the cabin.

The indictment accuses Manzanares of committing the murder "willfully, deliberately, maliciously, and with premeditation and malice aforethought."

If convicted, the maximum punishment Manzanares faces is life in prison, or the death penalty.

In court Wednesday, a U.S. attorney told the judge the government will need more time to review "a large dump" of evidence before determining whether to pursue the death penalty. Chloe Martin, a spokeswoman for U.S. Attorney Bryan Schroder's office, said that evidence included forensic material as well as accounts from passengers.

The next hearing on the case is scheduled for Sept. 22.