Stan Orenstein was heading to his Olney home when he received the radio call around 6 p.m. May 15, 1972.

Alabama Gov. George Wallace, the front-runner in the next day’s Maryland Democratic presidential primary, had been shot four times at close range at a campaign rally in Laurel and was being transported to Holy Cross Hospital in Silver Spring.

Orenstein, an FBI agent at the Montgomery County office, was to report to the hospital immediately and take charge of the investigation into the attempted assassination of one of the nation’s most visible and controversial political figures.

Nearly 40 years after the failed attempt of the gunman Arthur Bremer, to kill Wallace, Orenstein, 75, recounted the aftermath of an event that changed the course of American political history.

Known for his staunch resistance to the civil rights movement, Wallace won the Maryland primary. But his once-promising presidential campaign was effectively ended by Bremer’s bullets, which left Wallace paralyzed from the waist down.

It also influenced the man who once uttered the words “segregation now, segregation tomorrow, segregation forever” to reverse his views on race. In 1982, he admitted he had been mistaken about segregation during a fourth run for Alabama governor.

“I think in the ensuing years until his death, he always fell back on his experience in Maryland. It changed his life,” said Orenstein, who a few days later interviewed a recovering Wallace in a Holy Cross hospital room. Wallace died in 1998.

“When Bremer shot him, I firmly believe it made a sea change in his attitude,” Orenstein said.

It was the fifth shooting of a prominent American political or civil rights figure in a decade — the previous four claimed the lives of President John F. Kennedy, presidential candidate Robert F. Kennedy and civil rights leaders Rev. Dr. Martin Luther King Jr. and Malcolm X.

At the time of Wallace’s shooting, Bremer’s motive was unclear. Orenstein and his team raced to confirm Bremer was not a part of a larger conspiracy.

The investigation revealed Bremer, a Milwaukee man, wore Wallace campaign buttons and shouted to get the governor’s attention at a rally earlier that day at Wheaton Plaza. But a hostile crowd heckled Wallace and threw tomatoes at him. Because of the reaction, he refused to leave the podium to shake hands, denying Bremer the opportunity.

A few hours later at the Laurel Shopping Center, Wallace did shake hands against the advice of his Secret Service detail.

About 4 p.m. that day, Bremer emptied his gun into Wallace’s abdomen and chest. One bullet lodged in his spinal cord. Three other people — a Secret Service agent, an Alabama state trooper and a campaign volunteer — were unintentionally hit and wounded. Bremer was tackled to the ground and put in a headlock by Prince George’s County Police Cpl. Mike Landrum, who pushed him through an angry crowd for about 60 yards to a police cruiser.

“It happened so quickly. My strongest impression was how quickly events can change,” said Landrum, 68, now retired and living in Calvert County. Landrum remembered pointing out Bremer to a Secret Service agent before the rally. Prince George’s County police turned him over to the FBI early the next morning.

Orenstein arrived at the hospital to a chaotic scene. President Richard Nixon ordered the FBI to lead the investigation with Secret Service assistance. Secret Service agents and the press swarmed the building. Montgomery County police set up a security detail to protect Wallace and his party.

“We knew the Secret Service was distraught, frustrated. They had another protectee that got shot,” Orenstein said. “I knew there was going to be a lot of uncontrollable activity. This was big.”

Wallace underwent an operation that night. Don Black, a Montgomery County police sergeant working the Silver Spring midnight shift, drove to the hospital well after the news broke. The press converted the basketball court at the nearby Boys and Girls Club on Forest Glen Road into a command center. Close to 75 phone booths lined the gym, Black said.

“This was the first time that we placed police officers as guards at a private place,” Black said. “For the first few days, we’d pat people down.”

Black drove Wallace’s wife, Cornelia, and the family back to the Howard Johnson Inn in Wheaton.

A few days later, Orenstein and colleague Bill Campbell interviewed Wallace. Orenstein, who was assigned to the FBI’s Mobile, Ala., division in 1962 upon becoming an agent, had experience with Wallace. From 1963 to 1965, he visited Wallace whenever the U.S. Department of Justice opened a case against the state government. In 1963, Wallace gained notoriety for his “stand in the schoolhouse door,” when he attempted to halt the enrollment of black students at the University of Alabama by standing in front of a school auditorium.

Federal marshals and Deputy Attorney General Nicholas Katzenbach confronted him, and he stepped aside.

“I think it was strictly politics with him. He didn’t get any particular joy out of being brutal to black people and he wasn’t involved in that,” Orenstein said. “But the shooting changed his attitude toward black people.”

Orenstein entered the hospital room with an eight-photo spread, including Bremer’s arrest photo and similar-looking men from Orenstein’s previous bank robbery investigations. Wallace recognized Orenstein from Alabama and, after a few minutes of casual conversation to make sure the governor was lucid, the agents presented him with the photo array.

Wallace immediately picked out Bremer, and after dozens of interviews with witnesses from the Wheaton and Laurel rallies and the recovery of Bremer’s diary, the FBI was confident that Bremer acted alone. According to his diary, he acted out of a desire for fame, not for political reasons, and had targeted Nixon at an April rally in Ottawa, Canada. He was sentenced to 53 years in jail. In November 2007, at age 57, Bremer was released from the Maryland Correctional Institution in Hagerstown after serving 35 years.

Orenstein went back to working bank robberies and kidnappings before he retired from the FBI in 1986. He now lives in South Carolina. Next week, on the anniversary of the shooting, he’ll again look back at his incidental second meeting with Wallace.

“This situation was just unprecedented. There I was, going to Holy Cross Hospital, and there he was again,” Orenstein said. “It was a fascinating time and an incredible coincidence.”