The death of an Austin, Texas, policeman is being blamed on former Colorado resident Brandon Montgomery Daniel.Jaime De Luna-Padron died after being shot in the neck at about 2:30 a.m. Friday at a Wal-Mart in Austin.According to the arrest affidavit obtained by 7NEWS, the store manager called for police after an apparently drunken man appeared to be trying to stuff merchandise into a backpack.The affidavit said Daniel immediately tried to run when confronted by De Luna-Padron.The officer tackled Daniel, said Lincoln LaMere."This all occurred very quickly, the suspect either fired a shot at the officer as they were going down or as they hit the ground," said LaMere.According to the police account, "Daniel stated that he intentionally shot (the officer) in the region of the head."The affidavit said Daniel said, "I killed a cop."Reached by phone, Daniels mother, Mary ODell, told 7NEWS, "Everybody liked Daniel. He had everything. Im so sorry for all the losses, including the family of the officer."She said she had spoken with Daniel Thursday and that he had mentioned taking Xanax and drinking tequila.Court records show Daniel has had trouble with police before, including a theft arrest and several driving violations.O'Dell said Daniel also had recently been cited for DWI in Texas.Daniel graduated from CSU in December 2010 with a degree in computer science, a spokesman said Saturday.O'Dell said her son graduated with honors and had been on the "fast track" at Hewlett-Packard. She described him as a bright young man who was published in three science journals while still in college. But about three months ago, he began wrestling with a deep depression after a difficult breakup with his longtime girlfriend, she said. Daniel had not been behaving like himself recently and was charged with driving while intoxicated, his mother said.Daniel is being held without bond awaiting formal charges of capital murder, which could lead to the death penalty if he is convicted.De Luna-Padron was the first officer shot and killed in the line of duty in Austin since 1978. He worked at the department for more than three years and had previously worked for the Austin airport police and the San Angelo police department for 14 years.De Luna-Padron, a former Marine, was a veteran of the Gulf War. He leaves behind two daughters, ages 10 and 6.