Despite the fact that Bexar County Sheriff Javier Salazar has said that he believes Andreen McDonald is dead and that her husband is responsible, Andre McDonald is only charged with tampering with evidence. Salazar said investigators have found blood, an ax and a shovel with dirt on it at the McDonald home, the couple's Chevrolet Malibu, Andre McDonald's cellphone and his wife's old cellphone. Andre McDonald was arrested on suspicion of "altering, concealing and destroying" evidence, an arrest affidavit said. "He might be charged with tampering because the district attorney's office isn't prepared to prosecute him for homicide," said Geary Reamey, a criminal law professor at St Mary's University. Related: Andreen McDonald's mother bracing for worst Even if Andreen McDonald's body is never found, Reamey said Andre McDonald could still end up being charged with murder. Reamey admits not having a body poses legal challenges. "First, you have to convince the jury that a person was actually killed. Then, you have to persuade the jury that the killing was unlawful," Reamey said. For a murder conviction, prosecutors must show what type of homicide occurred. "We could have a negligent homicide, we could have a reckless killing, we could have an intentional killing. Those are all different types of homicides, and they carry different punishments," Reamey said. Andre McDonald is being held in the Bexar County Jail on $2 million bail. Reamey said $2 million bail is unusually high for a tampering with evidence charge and may indicate prosecutors may be trying to keep him behind bars while they build a bigger case. There is no statute of limitations for murder, so it could take months -- or even years -- for investigators to build a case.  Related: Missing woman described as fitness fanatic, motivator Even though there is no time limit, Reamey said because evidence deteriorates, the sooner the district attorney's office upgrades the charge, the better, if it wants a conviction. Crews will resume the search for Andreen McDonald on Saturday at Camp Bullis, eight days after she was reported missing.