The Farmers Branch police officer involved in an off-duty shooting is free on bond after being arrested Wednesday on one count of murder and one count of aggravated assault, according to Addison police.

Farmers Branch Police Officer Ken Johnson was taken into custody at 5:55 p.m., according to a statement from the Addison Police Department. The chiefs of both the Addison and Farmers Branch departments said Johnson was cooperating fully with their investigations.

Johnson said he was off-duty when he followed and shot two people he said he saw breaking into his personal vehicle. One of those two, 16-year-old Jose Cruz, died at the scene. The other burglary suspect, identified by family members as 16-year-old Edgar Rodriguez, was taken to Parkland Memorial Hospital in Dallas with injuries that were not considered life threatening.

"Based on our investigation thus far we had probable cause to make the arrest this evening," Addison Police Chief Paul Spencer said in a news release. "But this is a rapidly-evolving situation and it remains an active investigation. Therefore, we are refraining at this time from discussing the evidence collected thus far or about the specifics of this case."

The Farmers Branch police officer involved in an off-duty shooting has been arrested on one count of murder and one count of aggravated assault, according to Addison police.

Spencer said he expected the investigation to continue for several weeks. The Addison Police Department is working with the Dallas County District Attorney's office on the case as well as the county's public integrity unit.

Documents obtained by NBC 5 show Johnson's recommended bond amount was $250,000. He was later released after posting $150,000 bond -- a lower amount approved by a magistrate judge.

Jose Cruz's Family Reacts to Arrest

The family of Jose Cruz reacted to the arrest of Farmers Branch police officer Ken Johnson’s arrest.

News of Johnson's arrest was met with applause by hundreds of mourners attending a celebration of life service for Jose Cruz.

Although Johnson was not charged with capital murder, Cruz' mother had been pleading for answers and said she believes he deserves the death penalty. She spoke to the media through a translator.

"They're asking for the death penalty. We believe it's capital murder and that justice would be served by him having the same kind of punishment that he provided to her son," said family spokesman Carlos Quintanilla.

Family and friends of murdered teen, Jose Cruz, held a press conference about the arrest of Farmers Branch Police Officer Ken Johnson.

Family members said they were stunned that Johnson was arrested so quickly.

"We didn't think he was going to be arrested because he's a police officer and they have the power," said Cruz' cousin, Nora Rubi. "He should pay for what he did."

The family is working with a civil rights attorney, but Quintanilla said no decision has been made on whether they will file a lawsuit against Farmers Branch. Quintanilla also pointed out that Johnson was directly charged instead of the case being taken to a grand jury.

"Being so fast shows that the evidence was so overwhelming, and in many of the conversations that we had we basically said the evidence is so overwhelming that there's nothing that could be done except an indictment or an immediate arrest," Quintanilla said. "To bypass the grand jury and directly charge him with murder and aggravated assault, that speaks volumes for the case."

Ken Johnson's Attorney Responds to Arrest

By phone on Wednesday, Livingston called the arrest disturbing.

"The Addison Police Department has gone against decades of precedent in Dallas County of presenting these cases to the grand jury," Livingston said.

Livingston said Johnson was arrested at the Farmers Branch Police Department while being interviewed for the internal investigation. Livingston said he'd previously offered to turn Johnson in, if necessary. He questions why he was notified of the arrest after the fact.

"The only explanation for Addison's conduct and rush to judgment in this matter is that my client is a black police officer,” Livingston said.

Johnson, who was not injured, has been on paid administrative leave pending the results of the investigation. Fuller said Johnson and his attorney are cooperating fully in the investigations.

According to the Texas Commission on Law Enforcement, Johnson has worked for Farmers Branch police for a year. He worked as a peace officer for Dallas Area Rapid Transit for almost eight years before that.

Livingston previously told NBC 5 the shooting was justified because Johnson "felt that he was in fear of his life."

The Shooting in Addison

The chiefs for the Addison and Farmers Branch police departments say the investigations into a deadly shooting involving an off-duty officer are moving forward with the full cooperation of the officer and his attorney.

Johnson was off-duty when he fired his service weapon, killing 16-year-old burglary suspect Jose Raul Cruz Sunday night.

Officials said after Johnson saw his vehicle being burglarized in his Farmers Branch apartment complex parking lot, he got into his vehicle and chased the pair to the intersection of Marsh Lane and Spring Valley Road in Addison, where they spun out. An altercation took place, shots were fired and both of the men were hit.

Cruz was killed at the scene while the second person was transported to Parkland Memorial Hospital with injuries that were not life threatening. While police have not identified the second teen shot, his family has identified him as 16-year-old Edgar Rodriguez, a friend of Cruz.

Addison police are investigating the shooting, while Farmers Branch police are investigating the initial encounter as well as personnel issues.

The Farmers Branch and Addison police chiefs said at a news conference Tuesday that many details won't be revealed until their investigations are complete, including whether either juvenile had a weapon.

Farmers Branch Police Chief Sid Fuller noted department policies do not allow off-duty officers to chase suspects in their own vehicles.

Farmers Branch Police Pledge Thorough Investigation

The Farmers Branch Police Department continues an internal investigation into a deadly shooting involving an off-duty officer.

The fallout from Sunday's fatal shooting has hit the Farmers Branch Police Department hard.

"It's a bad situation for everybody involved. It's a tragic situation, but we have great men and women that work here as police officers for the city of Farmers Branch that continue to do their job," said Det. David Laisure.

While officers work their normal patrols the department continues its own internal investigation into Johnson's actions. Laisure promised a thorough and fair review of the case.

"We want to take our time to not rush it, to make sure all the evidence is presented and we have a complete investigation," he said.

While the incident is casting a shadow over the department Laisure said the incident is not a reflection of the work Farmers Branch officers do every day.

"Bad things happen, you know. It's how you deal with them. We have a small department and we work very well together. We have a great relationship, we're all brothers and sisters. They have their dedication. Their dedication is to the citizens of Farmers Branch and to this community. We all share that mentality," he said.

Johnson joined the department last year. Laisure has gotten to know him during that time, but would only say that he has not had any disciplinary issues.

Laisure said there is not a timeline for how long the internal investigation will take. The Addison Police Department continues to conduct its criminal investigation into the fatal shooting.

Ken Dewayne Johnson Warrant of Arrest and Detention

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NBC 5's Jocelyn Lockwood, Noelle Walker, Cory Smith and Meredith Yeomans contributed to this report.