Houston police said they had yet to determine a motive.
"It was kind of the All-American family, that's why we're trying to get down to figure out what's going on in this household," homicide detective Jimmy Dodson told KHOU. "The male of the family was an absolute hard-working breadwinner. He was an associate pastor in an area church. He's a great guy. The mother was apparently a great mother, according to family members. Like I said, it was kind of the all-American family."
Investigators who searched the home found a smoking gun next to a note next reading, "I've been watching you", according to KTRK.
Family members were at a loss to explain how something like this could happen, describing the family as "loving."
"There was nothing left out. There was no neglect or anything. There was nothing that even could possibly have justified this situation," Dawn Armstrong's cousin, Vaun Lee, told reporters. "This doesn't even make sense. It makes no sense."
Armstrong was named first-team Associated Press All-America linebacker in 1994 and was drafted in the sixth round of the 1995 NFL Draft by the San Francisco 49ers.
An ankle fracture in training camp led to his release that October. He signed with the Dolphins and played in four games with Miami that season, logging four solo tackles.
"Antonio was a special young man. He was an All-American and an outstanding player, but he was an even better person," his former head coach at A&M, R.C. Slocum, said in a statement. "He was such a positive influence on his teammates. He always had a great big smile and was a joy to coach."
Dawn Armstrong had just finished a seven day Facebook challenge posting pictures of her and her husband with notes about what she loved about him.
"This guy is my everything ... he is all that and some to me," she wrote.
