Huntsville, Alabama (CNN) -- An Alabama judge has found enough evidence to send the capital murder case against former university professor Amy Bishop to a grand jury.
Following a brief preliminary hearing Tuesday, Madison County District Judge Ruth Ann Hall ruled that there is probable cause that Bishop, 45, committed the crimes she is accused of -- capital murder and attempted murder.
Bishop, a Harvard-trained geneticist, is accused of gunning down her colleagues, killing three, at a February 12 biology faculty meeting on the University of Alabama's Huntsville campus. Three others were wounded, accounting for the attempted murder charges.
Madison County District Attorney Robert L. Broussard said the investigation is ongoing and estimates that his office will be able to present the case to a grand jury in about six months.
Dressed in a red jail jumpsuit, her wrists and ankles bound in chains, Bishop listened impassively to the testimony, occasionally shifting her glance from the witness stand to the prosecutor.
In an interview with police shortly after she was apprehended on campus, Bishop denied she attended the 3 p.m. meeting.
"I wasn't there. It wasn't me," she told police, according to Huntsville police homicide investigator Charlie Gray, the only witness to testify during the half-hour hearing.
"'I wasn't there' -- that kept being the repeated theme," Gray testified. "Every time we asked her a question about the shooting she would say, 'No way, no way. I wasn't there. It wasn't me.'"
The district attorney's questions focused on the timeline of events and evidence discovered at the scene that may indicate premeditation. A brief line of inquiry by defense lawyer J. Barry Abston focused on Bishop's state of mind before, during and the after the shootings.
In comments to the media before Hall issued a gag order, Bishop's lawyers indicated that the case will focus on her state of mind when she carried out the shootings.
Her denials aside, the biology professor appeared "calm" and "intelligent" during the police interview, agreeing to waive her Miranda rights and generally giving the impression that she understood what was going on, Gray testified.
Gray noted that Bishop questioned why she needed to speak to police.
"She wanted to know why she was there. She said she had a meeting at 4:30 to write a grant," Gray said. "She had to leave to make that meeting."
Witnesses told police that Bishop stood up about 50 minutes into a biology faculty meeting and opened fire without warning, shooting three people sitting closest to her in the head, Gray testified. They died at the scene.
The university identified the dead as Gopi Podila, chairman of the biological sciences department; Maria Davis, associate professor of biology; and Adriel Johnson, associate professor of biology.
She shot two others in the head and another in the collarbone before fleeing the room, the investigator testified.
A 911 call came in at approximately 3:57 p.m. and Huntsville Police apprehended Bishop at 4:09 p.m. at the northwest corner of the building, the Shelby Center for Science and Technology.
One of two witnesses who saw Bishop in the hallway after the shooting told police that Bishop asked to borrow his phone, Gray said. She used it to call a number later identified as belonging to her husband, James Anderson.
Police also found a 9 mm semi-automatic pistol in a trash can in the second-floor women's bathroom. It was left beneath tissues and a woman's jacket that had traces of blood on it, Gray said. The jacket was later identified as belonging to Bishop, he said. Tests showed that the blood was from the victims.
The gun had a 15-round magazine with seven live rounds and two jammed rounds, he said. In the meeting room where the shootings occurred, police also found a black satchel belonging to Bishop that contained another 15-round magazine.
The gun was traced to a friend of Anderson, Gray said. ATF agents interviewed the man, who said he purchased the gun in 1989 in New Hampshire at the request of Anderson, who lived with Bishop in Massachusetts at the time.
Anderson told the man that he was having problems with neighbors and asked him to buy he gun for him because Massachusetts had a waiting period to purchase guns while New Hampshire did not, Gray testified.
Asked after his wife's arrest whom the gun belonged to, Anderson denied that it was his, Gray testified.
In interviews with police after the shooting, the couple also provided nearly identical timelines of the day's events, Gray said. Bishop taught a biology class at 9:30 a.m., drove home and worked on a grant proposal until her husband drove her back to the university around 2:30 p.m., Gray said.
Anderson returned to the university after his wife called him, arriving around the same time as police, Gray said. He was also taken in for questioning.
"Did any witnesses report any unusual behavior prior to the shooting?" the defense lawyer Abston asked.
"I know her husband was with her and he said she had been a little depressed over tenure, but she appeared normal," Gray said.
Bishop had been denied tenure at the university a few weeks before the shootings.
So far, investigators have found no documentary evidence in journals or computer evidence to indicate Bishop had planned the attack, but Gray said there was still a lot of work to be done on the case.
In the wake of the massacre, information has come to light about Bishop's previous run-ins with the law. She faced criminal charges after an altercation at a Massachusetts restaurant nearly eight years ago, police said.
The police report says Bishop became furious that there was no booster seat available for her child, began screaming at the woman who had taken the last one and struck her in the head.
Authorities in Bishop's hometown of Braintree, Massachusetts, are also looking into the shooting death of her brother, Seth, in 1986. Bishop, then 20, said she accidentally shot her brother in the family's kitchen as she was trying to unload a shotgun, according to police reports.
The district attorney at the time regarded the death as accidental and declined to press charges. However, after the school shootings, the current district attorney in Braintree ordered a judge's inquest to re-examine the incident and determine whether charges are warranted.
In addition, The Boston Globe has also reported that Bishop and her husband were questioned in the 1993 attempted mail bombing of a Harvard Medical School professor.
Under Alabama law, Bishop could face the death penalty if she is convicted of capital murder.
Bishop's husband did not attend the hearing. Members of the media made up most of the courtroom audience, apart from a man who identified himself as a friend of the victims.
"They're having a hard time going back there," said Richard Hoover, a NASA astrobiologist whose office is located across the street from the Shelby building. "No one saw this coming."