HUMBLE — Sen. Ted Cruz has sought to make the NFL protests during the national anthem a flash point in his campaign. On Saturday, as Dallas police sorted out why an off duty officer killed a man in his own apartment, Cruz dug in.

Both Cruz and Rep. Beto O'Rourke agreed that a thorough investigation of the tragedy is warranted. But Cruz insisted that kneeling during the national anthem or showing disrespect to the American flag isn't.

"The facts in that Dallas shooting are horrific and tragic, and all of our hearts go out to the individual who was killed in his own home — and to the officer who presumably came home, from what I understand, from what's been reported, she thought it was her own home so she presumably believed there was an intruder there. That's a tragic circumstance," Cruz said when asked about the shooting and the protests during a campaign stop northeast of Houston.

Dallas officials said the officer thought she had entered her own apartment after working a night shift, and mistook 26-year-old Botham Jean, a native of St. Lucia who worked at Pricewaterhouse Coopers, as an intruder. The officer had also shot a suspect last year during an arrest.

"I expect that the legal system and law enforcement specifically will examine what happened and how everyone behaved. But that doesn't for a moment condone protesters disrespecting the American flag, disrespecting our national anthem," Cruz said.

O'Rourke has defended football players taking a knee during the pregame playing of the national anthem to draw attention to attacks on unarmed black Americans by police. Recent comments on the topic at a town hall meeting drew viral attention online. Celebrities lauded him, and Ellen DeGeneres heaped praise on him on The Ellen Show.

"I don't know that it vindicates anything. It's a tragedy, and it's a reminder that we continue to see unarmed black men killed in this country at an alarming rate," O'Rourke said Saturday after a rally in north Houston. "And there has to be a far better and more effective response than we have seen thus far. There has to be real accountability for the use of force. There has to be real justice at the end of these investigations. Wait till the facts come in to render any judgment on this, but I do think it's tragic and I know that as a country, we need to be able to do more."

Cruz linked the uproar to allegations that former President Barack Obama stirred suspicion against police.

The latest Dallas incident, he said, "also doesn't condone eight years under the Obama administration of demonizing and vilifying law enforcement."

"I am proud to support the men and women of law enforcement. Does that mean that police officers never make a mistake and never violate the law? No, of course not. ... And police are held to the law like everyone else," he said.

"You want to talk about black lives matter? Talk about enforcing the law in inner cities, in cities like Chicago, where African American children and adults are murdered by violence and homicide and gangs and illegal immigration," Cruz said, arguing that "demonization of police" only makes officers wary of doing their jobs, leaving citizens less safe.

"I think every life matters. Absolutely black lives matters. Absolutely blue lives matter. Every life matters, and the way to protect every life is to support law enforcement. Stop these criminals, stop these gang members and keep our communities safe," he said.