On Monday afternoon, a group of veteran officers on the Houston Police Department’s Squad 15 narcotics task force gathered at a small, tan, white-trimmed home of suspected heroin dealers to conduct a raid. It turned violent within minutes, and by the time the raid had ended, four of the officers had been shot and injured while the home’s residents—Dennis Tuttle and Rhogena Nicholas—were dead, along with their dog.

The shooting immediately prompted the expected response from law enforcement advocates and state leaders. Governor Greg Abbott offered prayers for the injured officers and characterized the incident as a “solemn reminder of the service and sacrifice our brave men and women in law enforcement make every day to keep us safe.” Lieutenant Governor Dan Patrick added in a tweet, “we must never forget to #backtheblue.”

Houston Police Department Union president Joe Gamaldi went a step further, calling out people who criticize the police. “We are sick and tired of having targets on our back,” Gamaldi said at a press conference on Monday night outside of the hospital where the injured officers were being treated. (All four survived their injuries.) “We are sick and tired of having dirtbags trying to take our lives when all we’re trying to do is protect this community and protect our families. Enough is enough. If you’re the ones out there spreading the rhetoric that police officers are the enemy, well just know we’ve all got your number now. We’re going to be keeping track on all of y’all, and we’re going to make sure to hold you accountable every time you stir the pot on our police officers.”

But in the following days, details revealed about the shooting have raised familiar questions about policing and use of force—in particular, the use of a controversial no-knock warrant.

Houston police chief Art Acevedo released the identities of Tuttle and Nicholas at a press conference the morning after the shooting. The couple had been married for twenty years, and neither of them had ever been convicted of a crime in Harris County. (Nicholas, 58 years old, had a misdemeanor “theft by check” charge dismissed in 2010 after paying $145 in restitution.) Tuttle, 59, was a disabled veteran who was honorably discharged from the Navy and had suffered from “debilitating injuries” for years, his sister told KTRK. Meanwhile, Nicholas’s first husband told the Houston Chronicle that she had never been into drugs. Neighbors, friends, and family expressed doubt that the couple could have been the dangerous heroin dealers described by the Houston Police Department. “I don’t buy it at all,” Tuttle’s sister told the Chronicle. “Not one hot minute.”

The home of Tuttle and Nicholas seems to have fallen short of the heroin dealer den police likely expected to find. According to the Chronicle, police recovered from the scene several guns and “small amounts” of marijuana and white powder that later tested positive for cocaine. Police have not said whether the guns were legally purchased, and the exact amounts of marijuana and cocaine found have not been publicly released. Though the household’s suspected heroin stash served as the main legal basis for the raid, there is so far no indication that officers found any of the drug.

On Wednesday, Acevedo released parts of the search warrant that allowed for the raid. According to the affidavit, the narcotics squad had been investigating the house for two weeks when they enlisted a confidential informant to go into the house and attempt to buy drugs (Acevedo said at a press conference Thursday that police received a tip earlier in January from an anonymous caller, who said her daughter had been inside the house doing heroin and that there were guns inside). At that point investigators did not know the names of anyone who lived inside the house, only that there was a man inside who looked to be around 55 years old. On Sunday, the officers met with the informant, gave him some money, and sent him inside the house to try to buy drugs. He returned with “brown powder” that later tested positive for heroin.

According to the affidavit, the informant said he bought the powder from the middle-aged man, who called it “boy,” a street name for heroin. The informant also said that the man carried a gun, and that there was more of the brown powder at the house, “packaged in a large quantity of plastic baggies.” The author of the affidavit wrote that the informant had “proven to be credible and reliable on many prior occasions” and he asked a municipal court judge “to enter the suspected place and premises without first knocking and announcing the presence and purpose of the officers executing the warrant.” As probable cause for the no-knock raid, the investigator wrote that because there was heroin inside and the man there was armed, it was reasonable to believe that the suspect would use the gun to defend himself or to buy time to destroy the drugs if he knew beforehand that police were going to enter the house. The order was signed at 1:30 p.m. on Monday. Within three and a half hours police had arrived at the house, armed and ready.

Acevedo described what happened during the raid at a press conference on Tuesday morning. According to Acevedo, nine narcotics detectives and at least six patrol officers surrounded the house before 5 p.m. on Monday. One officer broke down the door as a second officer, armed with a shotgun, stormed through and was immediately attacked by a pit bull, which he shot and killed. Meanwhile, Tuttle came from the back of the house and opened fire with a .357 Magnum revolver, hitting the second officer in the shoulder. As the officer collapsed onto a sofa, Nicholas approached him and reached toward his shotgun. Backup officers stormed into the house and shot Nicholas. Tuttle continued to exchange gunfire with the officers and was fatally shot.

The official HPD narrative is likely the only one we’ll have. Acevedo said that none of the officers had been wearing body cameras during the raid. Tuttle and Nicholas will never be able to tell their side of the story. It was a bloody end to a dangerous operation, made possible by a police tactic that is as controversial as it is common, particularly in Texas.

The Fourth Amendment protects against unannounced searches, except when law enforcement can show beforehand that there is a risk of violence or the destruction of evidence. Judges in Texas typically approve warrants for no-knock raids, and the tactic is frequently employed by police departments across the country, with mixed results. According to a 2014 ACLU study of twenty police departments, “no-knock warrants were used (or probably used) in about 60 percent of the incidents in which SWAT teams were searching for drugs, even though many resulted in the SWAT team finding no drugs or small quantities of drugs.” Many no-knock searches yield only enough drugs to charge suspects with misdemeanors, according to a 2017 New York Times investigation.

It’s a dangerous tactic. The Times found that between 2010 and 2016, 31 civilians and eight officers died during no-knock raids, while “scores of others were maimed or wounded.” The most notorious no-knock raid left a seven-year-old girl, Aiyana Jones, dead in Detroit in 2011. The ACLU’s 2014 report found that 42 percent of the subjects of SWAT search warrant raids were black and 12 percent were Hispanic. The Times also found that in some of the searches in which an officer was killed, “suspects with no history of violence, found with small quantities of drugs, have wound up facing capital murder charges, and possible death sentences.”

“It’s a use of force, it’s them taking people by surprise,” said Ashton Woods, the founder of Black Lives Matter Houston. “They want to over-police the community. They think they are preventing crime when they are really creating larger problems with community relations. It seems like a police state. They need to be reined in, and we need to know more about the way that they are policing.” Woods also noted that had Tuttle and Nicholas been minorities, their deaths likely would not have been so heavily covered by the media, nor would the incident have drawn such widespread criticism of the police.

Monday’s no-knock raid in Houston closely echoes a few incidents in Texas that drew national media attention. In March 2017, the New York Times covered two no-knock searches that left officers dead: one in Burleson County in 2013 and the other in Killeen a year later.

In Burleson County, a December 2013 raid on Henry Magee’s rural home left a Burleson County sheriff’s deputy shot dead. According to the Times, a sketchy confidential informant had told investigators that Magee had been growing marijuana in his trailer’s bedroom, with some trees reaching six feet high, and that Magee had several guns. Investigators did not properly vet the informant’s tip, failing to check the informant’s own criminal history or conduct a “controlled buy” (which is what Houston Police did by sending the informant in the Tuttle home to buy heroin). Five days later, they had a no-knock warrant approved by a judge, and ten heavily armed officers went to Magee’s trailer. “By about 5:40 a.m., the deputies were in place,” the Times wrote. “They wore uniforms as dark as the night sky, with lettering that revealed their identities—’Sheriff’s Office’—only on the back.” They used flash-bang grenades and found Magee inside, startled and holding a semi-automatic rifle, which he shot toward the front door, striking a deputy in the head. Magee surrendered once he realized the intruders were from the sheriff’s office. Investigators recovered a total of just 4.39 ounces of marijuana from the scene. There were no “six feet tall” marijuana trees. Magee was charged with murder, and while a grand jury eventually no-billed him, he was later sentenced to eighteen months in jail for felony possession of marijuana.

Marvin Guy was not so fortunate. In May 2014, Killeen police raided his apartment, acting on a tip that he was selling cocaine and carried a gun. Guy had a much longer and more serious criminal history than Magee, and after surveilling his apartment complex police requested a no-knock warrant, which a judge approved after reviewing it for only five minutes, according to the Times. A spate of home invasions in the area had Guy on edge, and the night before the raid he barricaded his front door with a chair and fell asleep with two firearms (illegally owned, since Guy was a convicted felon) by his side. At 5:40 a.m. the next morning, twenty armed SWAT officers arrived at the apartment complex. As they attempted to break in, Guy awoke to the sound of shattering glass, grabbed his gun, and began firing toward the door, thinking he was being robbed. The scene exploded with gunfire—Guy’s girlfriend later told the Times that it sounded “like the Fourth of July”—and by the time the shooting ended, one detective had been fatally wounded. After the raid, officers searched the apartment and found a total of just one gram of “suspected cocaine.”

“I was just trying to protect myself,” Guy told investigators after the shooting, according to the Times. “Nobody got on the loudspeaker and said, ‘This is the Police Department, come out.’ If they would have done that, I would have never grabbed a gun and started shooting. I thought it was some neighborhood kids trying to come in and do me harm… I just did what an average natural person would do.” Still, in 2014 a grand jury indicted Guy on counts of capital murder and attempted capital murder (Guy is black, and there were no African Americans on the grand jury). The case has stalled, and Guy has not yet gone to trial. The charges carry a potential death sentence.