Interim Fort Worth Chief of Police Ed Kraus says there's "absolutely no excuse" for an officer's fatal shooting of a woman inside her home over the weekend, even if she was holding a gun inside her home.

The officer, Aaron Dean, 35, resigned Monday. If he had not resigned, he would have been fired from the department, Kraus said.

Dean has retained Jim Lane to represent him. Lane, a prominent Fort Worth attorney, spoke with NBC 5 on Tuesday.

Lane calls the shooting of Atatiana Jefferson "a tragedy" and adds Dean says "he's sorry" and that the officer's family "is in shock."

An arrest warrant obtained Tuesday quoted the Jefferson's 8-year-old nephew as saying his aunt "heard noises coming from outside, and she took her handgun from her purse. The boy said his aunt "raised her handgun, pointed it toward the window" and "was shot and fell to the ground."

Reiterating that the shooting was inexcusable, Kraus said Tuesday, "the gun was found just inside the room, but it makes sense that she would have a gun if she felt that she was being threatened or that there was someone in the back yard."

Texas' castle doctrine law, on the books since 2007, is similar to many "stand your ground" laws and gives residents a strong legal defense to the use of deadly force in their homes if they perceive a threat.

Fort Worth Police Officer C.A. Darch, who was dispatched to the call with now-former officer Aaron Dean, is quoted in the arrest warrant as saying Dean was standing between her and the house and that she could only see his reflection in the window.

In body camera video released by the department, Dean is heard commanding, "Put your hands up. Show me your hands," before firing his weapon once. He is not heard in the video identifying himself as a police officer.

Dean declined to provide an interview on the night of the shooting and his legal counsel said he'd provide a statement at a later date. He did not provide that statement before he resigned Monday morning.

Chief Kraus recited a prayer during Tuesday morning's press conference and again apologized to Jefferson's family for their loss.

"Human life is a precious thing and should not have been taken from Ms. Jefferson," he said. "[To the public] I ask you please do not let the actions of one officer reflect on the other 1,700. There's absolutely no excuse for this incident and the person responsible will be held accountable."

While taking questions during a press conference Tuesday, Kraus grew emotional when describing the morale of the police department, saying while "officers are hurting" over the shooting, he has not encountered an officer who disagrees with the decision to arrest Aaron Dean.

"I don't have any officer saying this action should not have been taken against this individual, this officer. I'm getting the complete opposite response. 'Chief thank you for being quick and decisive. This is going to help heal us,'" Kraus said.

Kraus pleaded Tuesday with Fort Worth residents to not let the actions of one officer reflect on all employees of the Fort Worth Police Department.

"We have a great many officers who work extremely hard, every day. They do this at great sacrifice and with a servant's heart. I ask you to please do not let the actions of one officer reflect on the other 1,700. There's absolutely no excuse for this incident and the person responsible will be held accountable," Kraus said. "Human life is a precious thing, it should not have been taken from Miss Jefferson."

Kraus said Dean was arrested by Fort Worth officers at his attorney's office Monday night without incident and charged with murder. He was freed after posting $200,000 bond.

Attorney Lee Merritt, who has joined the family in several news conferences since Jefferson's death, spoke publicly again Tuesday asking for more information in what took place Saturday night.

While the family was glad to see an arrest, Merritt said they were unhappy he bonded out so quickly. He added the family wanted to know where the breakdown occurred that allowed the shooting to take place, asking if it was a problem with training, supervision or with call dispatchers.

Previous reports said a neighbor called a non-emergency number to ask for a welfare check for a neighbor whose door was open for several hours. The call was dispatched as an open structure call -- a difference Kraus said Monday and Tuesday would bring a different response from responding officers. The officers, Kraus said, are not aware if the call came in through 911 or by a non-emergency number, only how it's dispatched to them.

"The information came from the neighbor to the call takers, and then while it was relayed to the dispatch it was determined to be an open structure call. I can't tell you specifically if it was a dispatcher, but that's something we're looking into," Kraus said. "If they think that the structure is open due to somebody breaking in, that would elicit one response. If they think it's just somebody left their door open, that would elicit a different response."

Kraus' full statement from Tuesday can be read below.

I realize that no action we take can replace the loss suffered here. I'm deeply sorry for what occurred. I've received so many contacts from our officers who want to express how sorry they are as well and how this is not indicative of the work they do every day. Human life is a precious thing, it should not have been taken from Miss Jefferson. This incident has eroded the trust that we have built with our community and we must now work even harder to ensure that trust is restored. Concerning the status of the criminal investigation -- At approximately 6 p.m. yesterday, Aaron Dean was arrested for the murder of Miss Jefferson. We obtained an arrest warrant after enough evidence and facts were analyzed and verified. A team of officers quickly effected his arrest at the office of his attorney. He was booked into the Tarrant County Jail where his bond was set by the presiding magistrate. He has since posted bond. We're continuing to work closely with the Tarrant County Criminal District Attorney's Office to ensure this entire investigation is prosecuted in a thorough, meticulous and solid manner. To the citizens and the residents of our city. We understand your frustration and disappointment. I, too, am frustrated and disappointed by what occurred and the officer's actions. We never want an officer's response to a call to end in the loss of life. We have a great many officers who work extremely hard, every day, they do this at great sacrifice and with a servant's heart. I ask you to please do not let the actions of one officer reflect on the other 1,700. There's absolutely no excuse for this incident and the person responsible will be held accountable. Miss Jefferson's family and our community will have the last word -- the courts will speak on her behalf. Each and every one of you have our support and our commitment to serve you better. We strive to be better every day than we were the day before. My prayer for Atatiana's family, our community and our department comes from Numbers 6:24-26: May the Lord bless you and keep you. May the Lord's face shine upon you and be gracious to you. The Lord lift up His countenance upon you and give you peace.

Fort Worth is about 30 miles west of Dallas, where another high-profile police shooting occurred last year. In that case, white Dallas officer Amber Guyger shot and killed her black neighbor Botham Jean inside his own apartment after Guyger said she mistook his place for her own. Guyger, 31, was sentenced this month to 10 years in prison.

Relations with the public have been strained after other recent Fort Worth police shootings. In June, the department released footage of officers killing a man who ignored repeated orders to drop his handgun. He was the fourth person Fort Worth police had fired upon in 10 days.

Of the nine officer-involved shootings so far this year in Fort Worth, five targeted African Americans and six resulted in death, according to department data.

Nearly two-thirds of the department's 1,100 officers are white, just over 20% are Hispanic, and about 10% are black. The city of nearly 900,000 people is about 40% white, 35% Hispanic and 19% black.