Taylor Meyer, 27, was killed in Playa Del Carmen last November.
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He was with a group of friends who rented a condo in the city to celebrate a friend's birthday.
Oklahoma City police are looking for a man pictured in surveillance images, so they can figure out how Meyer's card ended up in that city. They're asking anyone with any information to give them a call.
"Either this person that withdrew the funds could have been involved in the murder, or he bought the card or was given the card from someone else," said father Kris Meyer. "But we feel, or at least I feel, that this person must have had his PIN number because he tried three or four times to get into Taylor's bank account."
Meyer's family is hoping the FBI will get involved in the investigation as Oklahoma City police work on identifying the suspect.