Hours after a notorious prison inmate managed to shoot five guards before being killed in a shootout, officials said Sunday they would probe how Samuel Sheinbein brought a gun into Rimonim prison, sparking the incident.

Sheinbein, serving a life sentence for the 1997 murder of an acquaintance in Maryland, opened fire around 3 p.m. Sunday, injuring three guards before holing himself up in a cell. Two more officers who responded to the scene were also wounded in an ensuing shootout.

One guard was critically injured and another was listed in serious condition. The other three sustained light to moderate injuries.

Two separate investigations, one by the Prison Service and another by the police, will attempt to answer a flurry of questions surrounding how Sheinbein acquired the weapon and managed to bring it into the tightly guarded prison, Israel Radio reported.

“It is utter neglectfulness that there is a pistol in a prison,” an unnamed Prison Service official was quoted by Ynet as saying. “It is neglectful that a murderer prisoner managed to acquire a weapon, and it is even more neglectful that no one managed to discover the gun.”

An initial investigation revealed that Sheinbein had gone on furlough two weeks before the shooting and had arranged to purchase a gun from an arms dealer, Channel 10 reported. Sheinbein then attempted to rob the gun from the dealer, but was not successful. He was arrested by police, who immediately returned him to jail.

Since then, Sheinbein attended two more hearings regarding his case. Police suspect that while away from prison during those hearings, Sheinbein acquired a firearm and smuggled it into the jail.

Prison Service officials insisted that Sheinbein did not receive the weapon from guards within the prison, Israel Radio reported.

Initial reports indicated that the suspect had grabbed the gun from a guard, but officials ruled that out, saying that guards did not carry weapons in the cell blocks.

Sheinbein was killed after barricading himself inside a cell for over an hour. After he shot at security forces, counter terror officers returned fire, critically injuring him, police spokesman Micky Rosenfeld said.

Hilal Bisan, the guard listed in critical condition, was fighting for his life Sunday night.

Bisan’s twin brother was killed during the devastating 2010 Carmel Mountains range forest fire, which burned down over 6,000 acres of woodlands and claimed the lives of an additional 43 people.

Nitzana Darshan-Leitner, who represented Sheinbein in 1997, bemoaned the “terrible tragedy” that befell the families of both the wounded guards and the shooter and challenged the system for how it has handled her client.

“When he was sentenced, he was 17, without a criminal background, a kid from a normal background,” she said. “It is hard to understand how after all these years in prison it was not able to help him rehabilitate.”

Sheinbein, an Israeli-American in his 30s, was convicted in the murder of Alfredo Enrique Tello Jr. outside Washington, DC, in 1997. Sheinbein gained Israeli citizenship after fleeing to Israel in the wake of the murder and successfully argued to be tried in Israel, where he received a lighter sentence than he might have in the US.

Samuel Sheinbein at Tel Aviv court in 1999.  (photo credit: AP/Eyal Warshavsky)

Samuel Sheinbein at Tel Aviv court in 1999. (photo credit: AP/Eyal Warshavsky)

Israel refused to extradite Sheinbein, prompting protests from senior US officials, including then-Attorney General Janet Reno. Some congressmen who had otherwise been friendly to Israel threatened to cut aid in response.

Following Sheinbein’s incarceration, Israel changed its laws to allow the extradition of Israeli citizens on condition that they are returned to Israel to serve any sentence imposed.