Leo Johnson poses for a portrait in Washington. Johnson was shot in the arm while at work at the Family Research Council when an intruder opened fire at the conservative-leaning think tank in downtown D.C. (Nikki Kahn/The Washington Post)

Leonardo Johnson knew something was wrong. After years working security, he could read the body language of visitors to the regal brick office building at the corner of Eighth and G streets.

Johnson was wrapping up his rotation at the front desk of the Family Research Council last summer when a young man came in and said he was interested in an internship. Johnson asked for identification. Instead of placing his bag on the counter, as most people do, the visitor crouched on the floor and reached inside.

As Johnson walked around to get a better look, the man pulled out a loaded semi-automatic pistol. Johnson was unarmed, with only his instinct and his weight behind him.

Thirteen months later, bullet holes are still visible in the building’s wood-paneled lobby. Slender scars are hidden under Johnson’s white dress shirt-sleeves.

On Thursday, Johnson and the shooter will be together for the first time since that August morning; Floyd Lee Corkins II is scheduled to be sentenced at the U.S. District Court in Washington. Prosecutors are seeking a prison term of 45 years; Corkins’s attorney is asking for 111 / 2 years, citing his client’s chronic mental illness.

Floyd Lee Corkins is seen entering the lobby of Family Research Council building on Aug. 15, 2012, in this security camera video while armed with a loaded semi-automatic pistol. Leo Johnson was at the front desk and was shot in the forearm, but was able to wrestle the gun away from Corkins. (Courtesy of Family Research Council )

To co-workers at the Family Research Council, the 47-year-old who grew up in Southeast is now “Leo the Hero.” The mass shooting at the Washington Navy Yard on Monday that left 12 people dead was a fresh, tragic reminder, Johnson’s colleagues and relatives said, of what could have happened if not for Johnson.

In February, Corkins admitted that he had targeted organizations he considered anti-gay and that he planned to kill “as many people as possible,” starting with the conservative think tank’s headquarters in Northwest, according to his signed plea agreement.

Corkins, who had volunteered at a gay community center in the District, was so angry with the anti-gay-marriage positions of the Family Research Council and the head of fast-food chain Chick-fil-A that he carried 15 sandwiches in his backpack and planned to “smother” the faces of his victims, according to court documents.

“Leo took a bullet for me. He took a bullet for the staff,” said Paul Tripodi, vice president of administration at the Family Research Council. A gold plaque in the lobby marks the spot of the struggle and the “heroic action” by Johnson, who “selflessly prevented a tragedy.”

It was all over in less than a minute. But not before Johnson almost pulled the trigger himself.

As Corkins rose from his spot behind the reception desk, he pointed his handgun at Johnson’s head and upper body. Johnson, who played junior varsity football at Ballou High School, shielded his face with one arm, ducked and charged.

Corkins fired three shots as the two men struggled. One hit Johnson in the left forearm. He kept going, pinning Corkins against a wall and punching him as hard as he could until he felt the grip on the weapon loosen.

“I knew I needed to get the gun. If I didn’t, he was going to kill me,” Johnson said as he walked through the crime scene with a reporter for the first time last week. “He didn’t come here to talk.”

Built like a linebacker, Johnson is known among co-workers and relatives as a gentle giant. Humble and mild-mannered, he bakes lemon cakes for his mother’s birthday and relishes spending hours behind a hot grill at his office’s annual summer picnic.

Johnson was raised, along with three cousins, by his mother and grandmother in a three-bedroom home in the Barry Farm housing complex in Southeast. His grandmother, who is now 103 years old, took the children to church most nights, just off Martin Luther King Jr. Avenue.

After high school, Johnson worked jobs in construction, retail and security. At the Family Research Council since 1999, he spent seven years as a security guard before becoming the building operations manager. He was finishing a morning shift at the front desk just before 11 a.m. on Aug. 15, 2012.

In the heat of his struggle with Corkins, Johnson’s adrenaline was pumping. His left arm had swollen to twice its normal size and he could not move his fingers. Still, he managed to wrest the gun from Corkins and force him to the ground.

“I thought I was paralyzed,” Johnson said. “I was enraged. I was going to shoot him. I was going to kill him.”

Corkins pleaded with Johnson not to shoot, Johnson recalled. He told him essentially, “It’s not about you,” it’s about the policies of the Family Research Council, according to court documents and interviews.

“But you shot me,” Johnson said he responded.

Johnson did not fire back. His faith intervened, he said: “The Lord spoke to me.”

In the months before the shooting, Johnson had gotten in shape. He took vigorous walks to the Washington Monument, lifted light weights and had shed about 40 pounds.

The shooting put Johnson in the hospital for a week after emergency surgery for the shattered bones in his forearm. He was back in the intensive care unit soon after for blood clots in his lung.

For weeks, Johnson couldn’t lift anything heavier than a coffee cup. At home in Oxon Hill, he leaned on his girlfriend of 13 years, Erica Reed, for the most basic tasks: getting dressed, preparing breakfast, taking out the trash.

There were painful, grueling weeks of physical therapy as he stretched, pulled and squeezed to regain motion and strength in his arm.

Johnson says he has never felt traumatized and views the shooting as an isolated incident. He has prayed often but did not seek professional counseling.

There were periods of anger and frustration, though, for a man who was used to taking care of things and taking care of everybody.

“He’s the crutch, he’s the support, so we all had to come together to support him,” Reed said.

Johnson was eager to get back to work when he returned in November. His family had reservations, but he assured them that his days of manning the front desk were over. The Family Research Council now relies on security from armed off-duty or retired law enforcement officers.

“I had it in my mind that it could happen again and didn’t want him to go back,” said his mother, Virginia Johnson, her eyes getting teary. “It was a little too fast.”

In April, Johnson had another surgery to replace four inches of bone in his left arm with bone from his pelvis. Metal plates remain permanently in his arm. There’s still discomfort, numbness where the bullet entered and pulsating pain if he overdoes it lifting heavy bags.

Johnson plans to be in the courtroom with his mother, girlfriend and dozens of employees from the Family Research Council when Corkins learns his punishment Thursday.

“It’s important to make a statement, to let everyone know the impact and how traumatizing it’s been for my family,” Johnson said. “I want to look in his eyes. I want to see if there is any remorse.”

Johnson initially struggled with the hero label. He didn’t want a big fuss and requested a private ceremony when Mayor Vincent C. Gray (D) awarded him the city’s first medal of honor.

“I’d like to think that anyone would have done what I did,” Johnson said. “I’m just Leo at the end of the day.”