An attorney for the family of a man shot at his home by an off-duty Dallas police officer said he believes authorities are trying to damage the victim's reputation by searching his home for drugs and other illegal items.

Investigators said in a search warrant of the apartment of Botham Jean, 26, that they were looking for “any contraband, such as narcotics, and other items that may have been used in criminal offenses.” Investigators later said in a court document that they found 10.4 grams of marijuana during Saturday's search.

Civil rights attorney Lee Merritt said Thursday the search shows that police want to besmirch Jean, who worked in risk assurance at PricewaterhouseCoopers and was a graduate of a private Christian university.

Botham Shem Jean was shot when a Dallas police officer returning home from her shift entered the wrong apartment in her building. via Facebook

“The warrant seems to only be designed for one particular purpose,” Merritt said, “and that is to smear the victim.”

Officer Amber Guyger, 30, was arrested Sunday on suspicion of manslaughter in the Sept. 6 shooting, which occurred when she returned home from work at night. She ended up on the wrong floor of the building and entered the apartment directly below hers, which belonged to Jean, according to her arrest warrant.

The warrant said the door was "slightly ajar," but Merritt said that would not be possible because the front doors shut automatically. He said he has had contact with three neighbors who heard Guyger knocking or pounding on the door.

The arrest warrant said it was dark, Guyger saw a figure she didn't recognize and the person did not comply with her commands. She believed "she had encountered a burglar," the affidavit for arrest states.

The story changed with the subsequent affidavit to search Jean's apartment, which said the officer "was attempting to enter apartment number 1478, with a set of keys."

Even so, authorities maintained in the affidavit, "The officer possibly believed the subject was an intruder. "

A witness heard shouting and then two shots, according to the document filed by Dallas police. Jean was rushed to a hospital, where he died.

Guyger was released from jail on $300,000 bond the day she was arrested.

On Monday, Dallas County District Attorney Faith Johnson said a charge of murder was possible.

Dallas police did not respond to NBC News' request for comment.

Merritt says he does not trust the inquiry and he scheduled a news conference on Friday to "denounce the lack of genuine transparency in the investigation," according to a statement.

He said the officer's home has not been searched.

"It’s clear to me and the family that investigators are not interested in doing an objective job," he said.