Investigators raided the veterinarian’s office of a woman suspected of murdering her husband, an Air Force staff sergeant and Lee native, after medical examiners discovered in his body high amounts of barbiturates found in medicines commonly used to euthanize animals, police said Thursday.

Phenobarbital and high levels of Pentobarbital were in the bloodstream of Michael Leslie Severance, according to a search warrant affidavit released Thursday by the Tom Green County criminal district clerk’s office in San Angelo, Texas.

Police seized four bottles of phenobarbital tablets and other drugs, Beuthanasia and Euthasol, that contain pentobarbital, in the veterinarian offices of Wendi Davidson during a search warrant execution Wednesday. Phenobarbital also is used to treat dogs for epilepsy.

Investigators took invoices, two unmarked bottles containing 33 tablets, drug log information and 21 file folders containing information on the treatment of 21 animals, the affidavit states.

The affidavit provides the first public clue as to what caused the death of Severance, whose body was found March 6, but officials from the Lubbock County medical examiner’s office have yet to say how Severance died.

It sheds further light on why police identified Davidson as a murder suspect, although she has not been charged with murder.

Many threads of the 3-month-old investigation are expected to converge when the cause of death is determined, said Lt. Curtis Milbourn, spokesman for the San Angelo Police Department.

“Things will become much more clear once we get a cause of death,” Milbourn said Thursday. “It’s too early yet in the investigation to say where we’re going with this.

“She felt a family member had done it [killed Severance], and that’s got to be looked into,” he added. “She may have done it, and that’s got to be looked into. He may have done it himself, [overdosed on drugs or committed suicide], and that’s got to be looked into.”

Investigators from the medical examiner’s office said they expect to release a cause of death within a few days.

Davidson reported Severance missing on Jan. 16 and filed for divorce the next day. Davidson, 26, was charged March 5 with tampering with evidence for hiding her husband’s body. According to police, she told her brother she had found her husband dead in bed on Jan. 15 and feared that someone in her family had killed him.

Davidson also wrote a friend of Severance’s in Florida the week before her arrest saying she thought Severance had disappeared in order to start a new life and that she had to get on with her own.

The body was found on property owned by Terrill Sheen, a former veterinarian believed to be San Angelo’s biggest landlord and who, sources say, has employed Davidson’s father as a contractor for about 20 years.

Davidson was released from jail Friday after posting a reduced $50,000 bail. Through an intermediary, she refused to comment on the case Wednesday.

Severance family members and friends reached Thursday strongly deny that Severance overdosed or committed suicide.

“It’s not a possibility at all,” said Nicole Leighton of Springfield, Severance’s stepsister. “He was a very happy person. He never once complained about his life in general. He was so happy. He had no reason to take drugs … Anyone that would have known Michael would have known that’s not a possibility.”

The speculation and the work to dispel it are the latest in a painful series of battles fought by the Severance family. Severance’s father, Leslie, had to push police to treat his son’s death as something more than a missing persons case and argued forcefully that his son was not a deserter. Leslie Severance has filed for custody of his grandson Shane Michael Severance in Texas civil courts. Family members and friends are raising money to help him pay legal expenses.

Now comes the idea that Severance might have committed suicide or overdosed.

“It tears us apart,” Leighton said. “We don’t want anything like that said about him. I guess we can’t get frustrated because they [police] can only tell us so much, so we do our best to handle it.”