An ABC News camera this week recorded Beresford-Redman driving into the garage of the home he once shared with his wife for the first time since she died.
When asked how he was holding up, Beresford-Redman replied, "I don't even know how to answer that question."
He was seen pitching a tent in the backyard while the couple's two young children watched.
His attorneys have said he left to avoid spending months, if not years, in jail while Mexican authorities build their case. He has yet to be charged with any crimes, but Mexican authorities have named him as a person of interest in his wife's death.
An attorney for Monica Beresford-Redman's sisters issued a statement saying, "the family is in shock."
"We plead that if he intends to run again that he not involve the children," the statement read.
Monica Beresford-Redman's sister, Jeane Burgos, now back in Los Angeles, told ABC News while she was in Cancun that "there is a part of me that was sorry I wasn't able to be there for her, to save her.
"But I want her to know," she said, "we are going to do everything, everything that it takes."