An Iowa couple claims the burger they got from a McDonald's drive-thru had marijuana on it.Watch video of this story"I've seen a lot of stuff, but never something like this," said Lt. Jason Bell of the Ottumwa Police Department. "I really haven't had a lot of investigations where I've focused so much on cheeseburgers."Ottumwa police said they are investigating the case. They said a man bought the burger for his pregnant fiance."They're alleging that they received some, an order from the McDonald's that had some suspected marijuana on the hamburgers," said Bell.Police said a sample of the substance was sent to the Division of Criminal Investigation for analysis. They said if the substance is marijuana it's a mystery why anyone would do this.Police said they are looking at everyone from the employees at the restaurant to the couple who reported the problem."We are exploring all possibilities at this point, and that factor is one thing we're considering with the investigation," said Bell. "It's more of a serious allegation against a business in the community. In any business, we want to make sure we come to the best possible conclusion on where it originated from."Police said they did find drug paraphernalia on an employee at McDonald's, but said no one has been charged in this case.Police said results of the substance found on the burger won't be available for at least a month.