Bruce Beresford-Redman, 40, is accused in the April 2010 killing of his 41-year-old wife, Monica.
"I feel relieved, you know, that he's going ... but I can't have good feelings about this whole process because everything brings me sadness," said Carla Burgos, the victim's sister.
Burgos said in a press conference that her family has been awaiting this day, but it doesn't ease the pain of having lost Monica.
Bruce Beresford-Redman was charged in the state of Quintana Roo with aggravated homicide. The couple had been vacationing in Cancun on a trip to work on their troubled marriage, according to her family. Monica Beresford-Redman's body was found nude and beaten at the resort three days after Bruce Beresford-Redman reported her missing.
Bruce Beresford-Redman was arrested on a fugitive warrant in Los Angeles seven months after her murder. He fought the extradition for about two years and was jailed at the Metropolitan Detention Center for about 15 months. On Wednesday, U.S. marshals put him on a place at LAX.
"After nearly fifteen months in United States custody, Bruce will finally be returned to Mexico to stand trial for Monica's murder. This day marks a major milestone in our journey to ensure justice for Monica," the Burgos family said in a statement. "It is our hope that Mexico will pursue his prosecution zealously and that once convicted, Bruce Beresford-Redman will be sentenced to the maximum term allowable by Mexican law."
Her family said losing Monica Beresford-Redman was bad enough, but believing her husband was responsible has been devastating.
According to an attorney for the Burgos family, Bruce Beresford-Redman will appear before a Mexican magistrate within 48 hours of arriving in Mexico City. Then, he will be tried in Cancun.
"He will be tried by a judge. There will be no live witnesses. Opposing sides present declarations for the judge to review, and then the judge makes a decision as to guilt or innocence," said Alison Triesel, the Burgos family attorney.
Triesel said if convicted, Bruce Beresford-Redmond could be sentenced to 30 years and spend it in a Mexican prison.
ABC News legal analyst Dana Cole said under Mexican law, there is no death penalty.
"Here, the burden is on the prosecution to prove you guilty. In Mexico, it's the opposite. The defendant, namely Mr. Beresford-Redmond, would have to prove his innocence," Cole said.
The attorney of Bruce Beresford-Redman said in a statement, "He has always stated that he is innocent of the charges against him, and it is his hope that the court in Cancun will assure that he receives a fair trial in which, he is confident, he will be exonerated.