Family members of a slain security guard said they are angry they have been given few answers regarding Saturday's shooting.

Jose Argueta, 37, was shot and killed when he showed up for work at a northwest Harris County strip shopping center on West Road at Veterans Memorial.

"This is really hard to believe this is happening to us because he was such a great person," said Maria Argueta, the victim's sister. "A brother, a friend, a son."

Argueta said her brother was a loving man who took care of his mother, his four children and worked two jobs. Argueta translated for her mother, Elva Argueta, who was devastated by the loss of her son.

"She says she can't understand why they had to shoot him in the head and shoot him in cold blood," said Argueta. "She doesn't even know if there was anything that could have been done for him to save his life."

Jose Argueta worked as a security officer for Texas Pioneer Control.

Sheriff's detectives said Argueta was shot and killed by a former co-worker, Gregory Griffin. Detectives said Griffin lost his job two weeks ago but kept showing up for work at the strip center and became angry when Argueta came to replace him.

"He kind of knew that this guy was really angry about him losing the job and he made a comment to family members that this guy seemed very dangerous," said Argueta.

Family members said they were also angry it took several hours to find out Argueta had been killed. Maria Argueta said the family was waiting for him to show up at his father's birthday party and when he was late and did not answer his cell phone, they had to call his employer to find out what happened.

"We're just so angry that we're over here thinking that my brother was ok working when he was already passed away," said Argueta.

Griffin has been charged with murder and is still in the Harris County Jail.