AURORA, Colo. -- A Texas fugitive wanted for allegedly killing his stepson and kidnapping his wife has been arrested in Colorado.

Brian Montez Booker, 37, was arrested at his relative's home in Aurora just after midnight.

Authorities in Texas say on Tuesday afternoon Booker kidnapped his wife, Yolanda Vanessa Booker, 37, while she was at work in Dallas. This was not long before or after he pulled his stepson, Joshua Henry, out of school, police said.

Relatives say Brian Booker called his brother in Lufkin, Texas, shortly thereafter and had said he planned to kill his wife and 14-year-old stepson.

This triggered a nationwide Amber Alert, which was called off when the boy's body was found near Dallas on Wednesday afternoon. The teen's body was found in a rural area off Main Street in Lancaster, Texas. Police there say Joshua Henry had been shot in the head.

Authorities say tips about Booker's whereabouts led them to a home in the 3000 block of Zion Street in Aurora. Aurora police surrounded the home after Booker's relative called at about 8 p.m. Wednesday, saying that he was there and he was armed. The relative told police he was afraid for the other family members in the home.

The other family members had left the home unharmed by the time the SWAT team and the Rocky Mountain Safe Streets Task Force, a group made up of FBI agents, arrived. At about 12:30 a.m., SWAT team members entered the home and confronted Booker. He failed to comply with their orders and officers used a Taser gun to restrain him.

Yolanda Booker was found inside the home unharmed.

Brian Booker's brother said the family knew Booker and his wife were having marital difficulties.

"I knew that him and his wife was having marital problems and that she was trying to get out of the relationship and I believe it escalated a little bit more than it should have," said Booker's brother Byron Finnie.

Authorities said that they had a suspicion that Booker would come to Colorado because he has family here and, until recently, lived here.

His family told 7NEWS that he was experienced with weapons but they never thought it would come to this.

"My brother was kinda in the law enforcement field. He worked at the Federal Reserve Bank as an armed guard. He worked as an armed guard with Denver Public Schools here for a number of years. This whole situation is kinda surprising to our whole family because this type of behavior isn't my brother's behavior. This is not in his character," said Finnie.

The couple also have a daughter who is staying with relatives, Lancaster police Lt. Joe Hall said.

Booker was held at the Aurora detention facility and he is now in the custody of the FBI. He will be extradited to Texas to face kidnapping and murder charges.