DALLAS (CN) – A Texas judge barred explosive testimony Wednesday by a lead investigator who said he believes fired Dallas police officer Amber Guyger did not commit a crime when she entered the wrong apartment and killed the unarmed black man inside.

Dallas County District Judge Tammy Kemp did not allow the jury to hear that portion of testimony from Texas Ranger David Armstrong, who headed the state agency’s investigation into the shooting death of Botham Jean, 26, at the South Side apartments on Sept. 7, 2018.

Guyger, 31, is charged with murder after she erroneously parked on the fourth floor of the complex, mistook Jean’s apartment for her apartment that was on the third floor and entered the ajar door before firing into the dark at what she believed was an intruder inside and striking Jean in the chest.

Even though Guyger was off-duty during the shooting, Dallas police asked for the independent investigation to allay fears of special treatment. Manslaughter charges were filed within days and Guyger was fired. The charges were upgraded to murder three months later.

On the witness stand, Armstrong disputed prosecutors’ argument that Jean was seated on his couch in front of the TV eating vanilla ice cream when Guyger shot him. Instead, Armstrong said Jean was 13 feet from the door and posed a “deadly threat” to Guyger.

Outside the presence of the jury, Armstrong said Guyger acted “reasonably” and that he does not believe she committed any crime.

On cross-examination, defense attorney Robert Rogers, with Lyon Gorsky in Dallas, focused on side-by-side images Armstrong took of Jean and Guyger’s apartments and floors to emphasis the layouts were identical and how apartment numbers were not at eye level and placed to the side.

Armstrong admitted that he even had difficulty determining what floor he was on during his investigation of the crime scene, saying a black sign near the elevator of the parking garage was the only marker of the floor.

He added that 46 residents that were interviewed stated they had been on the wrong floor before and tried to enter the wrong apartment with their keycard, the majority of whom lived on the third or fourth floor. He said 93 residents admitted to parking on the wrong floor before, and most of them also lived on the third or fourth floor.

Assistant District Attorney Jason Hermus objected to the testimony of his own witness, arguing that Armstrong’s conclusory statements and speculation about Guyger’s state of mind and where Jean was shot would only serve to confuse the jury. The judge sustained the objections.

The bulk of Armstrong’s testimony centered on the technical details of the crime scene. He testified that a strike plate built into the frame of Jean’s front door was defective and failed to lock the door shut when Jean returned home about 20 minutes before the shooting. Guyger was able to enter the ajar door and her apartment’s keycard was found inserted into the lock when investigators arrived.

Jean’s neighbor, Whitney Hughes, echoed Armstrong’s findings when she testified Wednesday afternoon that her front door often does not close completely and malfunctions.

Armstrong’s testimony was briefly delayed in the morning after a female juror disclosed that she had a professional business relationship with the Ranger. Judge Kemp declined to dismiss her after quizzing the juror in private about the relationship and whether it would impact her judgment of the case.

Several of Jean’s neighbors testified that they only heard the two gunshots and no commands being yelled or any commotion immediately before, disputing defense claims that Guyger yelled instructions at Jean before shooting him.

The judge briefly recessed late Tuesday during the emotional testimony of neighbor Joshua Brown, who had met Jean one day before his death. He began weeping when talking about hearing Jean singing gospel songs in his apartment every morning. Brown testified that he heard shouting as if “two people were meeting each other by surprise” before hearing the gunshots.

Another neighbor, Ron Jones, testified Tuesday that he observed Guyger’s white pickup truck driving fast around a corner in the parking garage.

The prosecution has argued that Guyger was distracted by sexually explicit messages she exchanged with a fellow officer that indicate they may have planned on having a romantic encounter later that evening. During opening statements, Hermus said the sexting caused Guyger to miss several indicators that she was entering the wrong apartment, including the fact that Jean had a large red mat at his door that Guyger did not have at her door.

Guyger’s defense has argued she made a reasonable “mistake of fact” in entering Jean’s apartment and his death was a tragic accident. Rogers claims Guyger reasonably deemed Jean a threat and that she shot him in self-defense.

Also Wednesday, Judge Kemp apologized to members of Jean’s family in the gallery due to not informing them of body camera footage of a dying Jean being played a second time. Jean’s parents, Bertram and Allison Jean, of the Caribbean country of St. Lucia, stood up and left the courtroom when it was first played Tuesday.

Guyger entered the courtroom in a pink blouse and blue sweater, flanked by sheriff’s deputies and her attorneys. She remains free on bond. She wept silently Tuesday as her frantic 911 call was played, as she is heard repeatedly saying she thought it was her apartment while apologizing to a dying Jean. She faces up to life in state prison if convicted.