Deputy Darren Goforth's death raises a sobering question: Are more officers getting killed because of a "dangerous national rhetoric" against police?

"This rhetoric has gotten out of control," said Goforth's boss, Harris County, Texas, Sheriff Ron Hickman. "We've heard 'Black lives matter,' 'All lives matter.' Well, cops' lives matter, too. So why don't we just drop the qualifier, and just say 'Lives matter,' and take that to the bank?"

The phrase "black lives matter" rose to prominence in 2013, when Trayvon Martin was shot and killed by George Zimmerman. It gained more traction last year, when Michael Brown was killed by a police officer in Ferguson, Missouri, and Eric Garner died after an apparent chokehold by a New York police officer.

But whether the outrage over perceived police brutality against African-Americans played a role in the seemingly random killing of Goforth is up for debate.

First court appearance

Shannon J. Miles is accused of killing Deputy Darren Goforth.

Shannon J. Miles has been charged with capital murder for the death of Goforth, who was filling up his patrol car Friday night at a Houston gas station when he was shot in the back.

Even after Goforth fell to the ground, authorities said, the gunman stood over him and kept firing.

A heated debate

Hickman acknowledged that the motive for his deputy's death has not been determined.

But while some lauded the sheriff for saying anti-police rhetoric has gotten "out of control," others said he unfairly and prematurely linked Goforth's death to the "Black Lives Matter" movement.

"There's no evidence that there's a connection between this rhetoric, or this sort of national discourse ... and what happened," CNN political commentator Marc Lamont Hill said. "It's an awful tragedy, but I don't think it's connected."

But CNN law enforcement analyst Harry Houck said the anti-police rhetoric is undeniable, citing a protest in Minnesota over the weekend in which demonstrators held a banner saying "Black Lives Matter" and chanted, "Pigs in a blanket! Fry 'em like bacon!"

Texas state Rep. Garnet Coleman said it was "unfortunate" that the sheriff tied Goforth's death to the "Black Lives Matter" movement -- or anything that has to do with police brutality -- so quickly.

But he also said the sheriff had a point.

"In general, I think the overall rhetoric is overheated, and it only leads to more injury and death," Coleman told CNN's "New Day" on Monday. "We're going to have to figure this out, whether it's training for police or having a sit-down to decrease the rhetoric -- particularly if it discusses violence at all."

Ambush killings of cops on the rise

In 2014, 15 officers were shot and killed in ambush attacks, the National Law Enforcement Officers Memorial Fund said in December. That's triple the number of officers who were killed in ambush shootings in 2013, the group said.

NYPD officers carry the casket of slain officer Wenjian Liu on January 4.

Last December, New York police officers Wenjian Liu and Rafael Ramos were fatally shot while sitting in their squad car. Police said the gunman declared on social media his intention to kill officers as revenge for the deaths of Brown and Garner.

"I'm Putting Wings On Pigs Today," suspect Ismaaiyl Brinsley allegedly wrote on Instagram. "They Take 1 Of Ours, Let's Take 2 of Theirs."

So far in 2015, several officers have been killed in ambush attacks in addition to Goforth.

In Georgia, Fulton County police Officer Terence Green was shot while responding to reports of gunfire in a neighborhood in March. Police said the gunman "appeared to have gone on a rampage" and ambushed Green with an assault-style rifle.

In Louisiana, New Orleans police Officer James Bennett Jr. was fatally shot while sitting in his car.

Outpouring of support

Mourners created a memorial at the gas station where Goforth was killed.

If there was any hostility toward Goforth because of his job, it was quickly outweighed by the support of thousands of strangers.

As of Sunday night, donors dropped off more than $50,000 for the Goforth family at the gas station where the deputy was killed, organizer Brian McCullar said.

And a gofundme.com page raised more than $70,000 in one day.

"This was a very senseless murder and no one, be it of any race, deserved to die like this," Kimberly Bourda Murphy wrote on the page. Goforth's life "did matter, just as all lives matter."

CNN's Faith Karimi, Sam Stringer, Nick Valencia and Kari Pricher contributed to this report.