The same gun was used to kill two homeless men who were shot as they slept, wrapped in blankets on the streets of Atlanta in separate slayings last month, according to Atlanta police.
Now, police hope the bullets will lead them to the killer.
Law enforcement agencies nationwide have been alerted, but none have reported crimes that match the seemingly senseless and random Atlanta shootings, Detective David Quinn said Wednesday.
A type of .45-caliber bullet with an elongated shape often called a "cowboy bullet" was used each time, he said.
In the first killing, Dorian Jenkins, 42, was found dead in a blanket on a sidewalk Nov. 23. In the second, Tommy Mims, 68, was shot while curled up in a blanket Nov. 26. Both were likely shot repeatedly early in the morning in what Quinn describes as "overkill."
Jenkins was shot five times and Mims was shot seven times, Quinn told a news conference at police headquarters. He added that the gunman would have had to stop after five or six shots and reload as Mims was dying on the pavement to fire additional shots.
"It's sinister. It's evil in that there was nothing to gain from it monetarily," Quinn said, adding that most homicides in Atlanta involve robbery or the resolution of an ongoing dispute or debt.
Quinn said a group of teenage outreach workers who feed the homeless found Jenkins' body and called police. Mims usually collected cans for money and someone went to check on him after he failed to show up at a local recycling center as usual, Quinn said. The detective later added that he had to notify Mims' relatives of his death on Thanksgiving eve.
Homeless advocates have been warning people to be on guard, and Quinn has been out on the streets on recent nights urging Atlanta's homeless to be extremely cautious "until we know what we're dealing with," he said.
"This reminds me of the David Berkowitz case when I was kid up in New York," Quinn said, referring to the man known as Son of Sam, who used a revolver to kill six people in the mid-1970s.
In Atlanta, Quinn said, "this guy is shooting homeless people who are sleeping in the wide open."
Quinn said he doesn't believe the shooter knew who he was aiming at because the men were covered to keep warm. "It was just a human being inside a blanket," Quinn said.
"It looks like these guys never woke up," he added.
Police on Wednesday released photos of the bullets and the Blazer Ammunition packaging mostly black with a red stripe in which they were sold. Experts believe they were fired from either a Taurus Judge revolver or a Smith & Wesson Governor revolver, Quinn said.
"The gun and the bullet are both equally important in terms of turning this case," Quinn said. "We don't see this gun on our crime scenes on a normal basis," he said, adding that most people who own the type of gun used in the killings have it for home defense purposes. The particular ammunition used in both slayings was discontinued in 2010, Quinn said.