The discovery led FBI agents to intercept the Carnival Elation cruise ship while it was at sea and interview dozens of witnesses, including Robert McGill. During questioning, the school teacher from Los Angeles told investigators he killed his wife "in the bathroom of their cabin with his bare hands," court documents revealed Friday.
McGill made the confession after being informed of his Miranda rights and telling interrogators he was willing to answer questions without the presence of an attorney, FBI Special Agent James B. Stinnett wrote in a probable cause affidavit attached to the criminal complaint charging him with one count of murder.
Calls to McGill's attorney were not immediately returned. At his court appearance earlier in the day, she declined to comment on the case.
McGill is charged with killing his wife on Tuesday, the day of his birthday, as the ship steamed home after a stop in Cabo San Lucas, Mexico. U.S. District Magistrate William McCurine Jr. entered a plea of not guilty on McGill's behalf, as is common practice in federal court at initial appearances.
McGill was distraught during the brief hearing and argued with federal public defenders about whether he could make a statement to the court as his family members sobbed in the gallery. He appeared without handcuffs and wore a white jumpsuit.
"They're suffering now," McGill was heard saying as he gestured to his family. "I don't think it is for the best. I think they are suffering and need to hear from me."
"That's putting more financial burden on top of the pain and horror that I've caused this family," he added before the hearing resumed.
It wasn't immediately clear to what McGill was referring.
McGill's family, including two adult sons, declined to comment after the hearing, as did Assistant U.S. Attorney Joanna Curtis.
Shirley McGill turned 55 just six days before she died. The San Diego County medical examiner's office said she died of strangulation and blunt force injury to the head and torso.
Stinnett noted in the court papers that Robert McGill's knuckles "appeared as if he had been in a fight."
Friends and neighbors said they were shocked to learn of the charge.
"Bob and Shirley never said anything negative about each other," Michael Hougardy, a neighbor in McGills' cul-de-sac in the San Fernando Valley area of Los Angeles, told The Associated Press. "I saw Bob a couple days before they left. He was excited. He was looking forward to it."