Philadelphia Police believe Joseph Wamah Jr., 31, was killed almost two days before the mass shooting in Philadelphia's Kingsessing neighborhood that killed four others.
CNN  — 

One of the five people allegedly killed by a lone shooter in Philadelphia last week is believed to have been fatally shot almost two days before the others, according to police, raising questions about whether the second attack could have been prevented.

The suspect, Kimbrady Carriker, allegedly shot and killed 31-year-old Joseph Wamah Jr. early on July 2 – about 44 hours before he allegedly carried out a shooting rampage in the Kingsessing neighborhood, Philadelphia Police said in a news release Sunday.

Early that morning, police received a report of gunshots near 1600 South 56th Street, the release said, but officers were dispatched instead to the 1600 block of North 56th Street – about three miles away. As a result, they did not find evidence of a shooting.

“Hindsight is always perfect,” Police Commissioner Danielle Outlaw said in a news conference Monday, when asked whether the first shooting presented an opportunity to prevent the one that followed.

“While it may have given us an investigative lead, the likelihood of cutting that off, or cutting off what happened later on, we just don’t know,” Outlaw said. “It’s tragic, it’s unfortunate. And we don’t like the fact that we’re adding to the atrocities that already occurred, because now folks are second guessing our actions. But the answer is we really don’t know.”

Police became aware of the error in the days that followed the July 3 mass shooting, Deputy Commissioner Frank Vanore said at the news conference, as investigators went door-to-door to gather more information. On Friday, a witness told detectives they heard gunshots that night inside a home in the 1600 block of South 56th Street.

Detectives then encountered more witnesses, one of whom said they called 911, Vanore said. Police initially could not find a record of that call but located it using the caller’s phone number, he said, then realizing officers had been sent to the wrong location.

Police then discovered video evidence of the July 2 killing, Vanore said, describing footage of a shooter opening fire and entering the home where Wamah was found. It’s unclear why Carriker allegedly targeted Wamah or that address.

But police believe the call about that shooting came an hour-and-a-half later, indicating they believed it unlikely Wamah would have still been alive if police were dispatched to the right location.

The medical examiner’s office also confirmed, Vanore said, it believed Wamah died long before the four other victims, who were previously identified as DaJuan Brown, 15; Lashyd Merritt, 20; Dymir Stanton, 29; and Ralph Moralis, 59.

Several others were injured in last Monday’s shooting, including 2- and 13-year-old boys, who police said were shot in the legs. A 33-year-old woman and another 2-year-old – the twin of the first – were injured by glass.

Carriker, 40, faces charges of murder, attempted murder and carrying a firearm without a license, among others in connection to the shooting. He had a preliminary arraignment last Wednesday but was not asked to enter a plea. He is being held without a bail, and a preliminary hearing is scheduled for July 24, according to court records.

The Philadelphia Public Defender’s Office, which is representing Carriker, previously declined to comment on the case.

The revelations about the timing of Wamah’s killing have not affected the charges Carriker faces, according to a statement Sunday from District Attorney Larry Krasner, adding Wamah’s family was briefed on the findings.

“I cannot express enough the sorrow I feel – and that surely all the officers and detectives working on this investigation must feel – that these developments may be confusing and re-traumatizing for Mr. Wamah’s loved ones,” Krasner said.

Authorities believe the shooting was premeditated; Krasner previously stated it was “obviously planned.” He also told CNN last week the suspect’s social media history contained indications of “mental health issues” and “irrational behavior.”