That raid — and its outcome — mirrored a 2005 Baltimore County police action, in which officers equipped with a battering ram and flash grenades stormed into a Dundalk home to search for drugs. In an upstairs bedroom, a 44-year-old woman pointed a revolver at Artson and he fired three rounds, killing her.
Although deaths mark a small percentage of the more than 1,600 tactical deployments conducted each year in Maryland, critics say that such raids have become too common and that the units should receive greater public scrutiny.
"SWAT teams are very traumatic. It's not the same thing as having an officer come to your door," said Berwyn Heights Mayor Cheye Calvo, the target of a misguided raid in July 2008.
Sheriff's deputies burst into his home with automatic weapons, handcuffing him and fatally shooting his two dogs. A review of the raid found that police targeted Calvo's home after drug dealers sent a package of marijuana to him and other unsuspecting homeowners; the dealers hoped to collect the packages before the homeowners did.
Calvo was cleared of any wrongdoing, and a lawsuit against Prince George's County was settled for an undisclosed amount.
That highly publicized incident prompted state legislators to require police departments to submit data every six months on tactical deployments, starting in 2010. But Calvo and others say the data is not thoroughly analyzed, so it's difficult to determine patterns and problems. Calvo notes, for example, that Howard County reported a 72 percent increase in the use of tactical units from calendar year 2010 to 2011, though the increase is not apparent in the state compilation, which is based on a fiscal year.
Police officials say such deployments provide the safest option, especially when dealing with potentially armed and dangerous suspects.
"In general, tactical units are used for high-risk warrant services," said Cpl. Cathy Batton, a Baltimore County police spokeswoman. She would not comment on the Reisterstown raid, saying the warrant was sealed. She said, "It's not just officer safety, it's the safety of everyone involved," adding that officers get highly specialized training to handle potentially volatile situations.
Capt. John McKissick, commander of the Special Operations Bureau in Howard, said, "These numbers tend to fluctuate," so it is difficult to draw conclusions from only two years of data. He added that the county has reported fewer deployments for the first six months of 2012 than in the same period last year.
Tactical units frequently force their way into homes, sometimes without announcing their presence. The teams were created to handle particularly dangerous situations, such as serving warrants on violent offenders or drug gangs, and dealing with hostage or barricade incidents. Many carry high-powered rifles, and they typically are outfitted with bullet-resistant vests, helmets and shields.
According to the most recent report from the Governor's Office of Crime Control and Prevention, total deployments rose marginally, from 1,618 to 1,641, from fiscal 2010 to 2011. The Prince George's County Police Department had the most, with 343 deployments, followed by Baltimore City with 289, Montgomery County with 139, and Baltimore County with 120.
In each of the two years that the reports have been issued, deployments resulted in a civilian death and more than a dozen injuries. A handful of animals were killed or injured as well.
"On the face of it, with that many involvements from the SWAT Teams, while nobody wants to take a life at all, that doesn't seem like an alarming number [of fatalities] considering the type of people that they're dealing with," said L. Douglas Ward, director of the Division of Public Safety Leadership within the Johns Hopkins University School of Education.
He urged further study, however, to find out "what's behind the numbers," including whether the injured were on the attack when they were hurt, or simply innocent bystanders.
"Statistics are a good tool to get you to ask more questions; they're not going to tell you the whole story," Ward said. Tactical team raids "serve a good purpose, but like anything else, they have to be [based] on good policies and good training, and I think people in general have a right to know if they're being used safely and properly."
The governor's office, which receives the annual report, agrees the data alone don't say much.
"We can't draw conclusions about whether a deployment was necessary or reasonable: Those details are just not reported, the incident-based details," said Raquel Guillory, a spokeswoman for Gov. Martin O'Malley.
She said the office might request that kind of information in the future. In the meantime, the governor and his staff continue to review the statistics, looking for significant changes that would require further examination, she said. So far, the figures have been steady.
Still, critics point to examples such as a 2009 raid in Howard County, when the resident of an Elkridge mobile home said officers hit him in the face with a shield, knocking him to the ground, and shot one of the family dogs.
Police were searching for a high-powered rifle and nearly 150 rounds of ammunition that had been stolen from police cruisers in a nearby neighborhood. Police said an informant told them that the stepson of the mobile-home resident might have been trying to sell an assault rifle, but they did not find the rifle or ammunition.
In the July raid in Reisterstown, police wanted to serve a search warrant in an attempted-murder case, and the suspects were facing concealed-weapons charges.
"Police officers are alive because of [the tactical unit's] existence and how well trained they are," said Cole B. Weston, president of the Baltimore County Fraternal Order of Police. "If you did not have them, or their expertise, you would lose more police officers."
But critics, including Calvo, said that while some cases might warrant tactical deployments, the raids are too frequent.
"These quasi-military tactics used by police departments are unnecessary in most investigations," said Brian G. Thompson, a Baltimore County defense attorney who has represented clients whose homes have been raided.
Fatalities and injuries are inevitable when such tactics are used because "people don't know what was happening," Thompson said. Even when police have identified themselves, residents are startled awake and a natural reaction is to reach for a gun, he said.
"There's certainly a place for these tactics, but more often then not, [police] can conduct surveillance" instead, he said.
Tim Lynch, director of the Cato Institute's Project on Criminal Justice, agreed, saying there has been an alarming increase in the use of tactical units across the nation.
"It's gone from an exceptional set of circumstances to routine police calls," he said, listing deployments around the country for matters ranging from graffiti to child pornography.
Police, he said, "need to do the investigations," which might reduce mistakes such as identifying the wrong address. He said that in many instances, officers could wait until the suspects walk outside to avoid endangering innocent people inside.
He applauded Maryland's effort to track how often and why tactical units are used.
"Law enforcement around the United States are heavily decentralized. There are no statewide rules governing use" of tactical deployments, he said. "That's why that reform has kind of stood out."
He added, however, that "much more needs to be done here about when police raid our homes. The great American principle is that our homes are our castles."
Calvo said the next step is for the state to conduct more in-depth analysis of the data on raids. He says that looking at data on a calendar-year basis, which the state does not compile, deployments have risen 13 percent, from 1,526 deployments in 2010 to 1,722 in 2011.
He'd like to see legislators create a task force to evaluate the findings, potentially adopting a best-practice standard for departments to follow when deploying tactical units.
He's concerned about the number of deployments used in nonviolent cases such as drug investigations.
"You have to have data to give you a sense of what's going on here," Calvo said. "You need to have policies in place when police are taking action that people can monitor."
Baltimore Sun reporter Tricia Bishop contributed to this article.