“We want to know: Why? What happened?”

So many questions, so much we still don’t know about the case of the woman shot to death by the Secret Service and the U.S. Capitol Police on Oct. 3, 2013, after a car chase from the White House to Capitol Hill. Her 13-month-old daughter survived in a car seat.

“Did we miss something?”

Barbara Nicholson is asking. The office manager of a dental practice in Ardsley, N.Y., is standing in the hygiene room, remembering the woman who used to clean teeth at this chair. Miriam Iris Carey — that was her name. She was one of the best dental hygienists and “one of the nicest people” Nicholson ever hired.

“We’re left with a void and no answers,” Nicholson says. “It’s like she was wiped off the face of the earth.

Nicholson’s voice catches. She pauses and looks away. “She’s missed. She’s very missed.”

Do you remember Miriam Carey? Her remarkably public death at 34 mesmerized us for a couple of news cycles. Then we moved on pretty quickly. I had to look up her name when I first started puzzling over this case. The main thing I remembered was that incredible video — the one showing the two-door black Infiniti surrounded by Secret Service officers with guns drawn near the Capitol Reflecting Pool. The car looks trapped. Suddenly the driver backs into a squad car and accelerates away. There’s the sound of gunfire while tourists take cover on the West Lawn. The Infiniti reappears, making a loop around a traffic circle, and proceeds up Constitution Avenue to what would be the fatal encounter outside the Hart Building.

What an afternoon. We were told that Carey “rammed” White House and Capitol “barriers.” That she tried to breach two security perimeters. That she had mental problems.

District Police Chief Cathy Lanier said federal officers acted “heroically.” The House of Representatives offered a standing ovation.

It was easy to call this a tragedy and turn the page.

Except that some of what little we thought we knew hasn’t held up. The part about ramming White House barriers and trying to breach two security perimeters? Not exactly true.

And how did a supposedly mentally unstable person remain a longtime, reliable and valued employee at two dental practices until the day she was killed? She had a condo and a family and, according to colleagues and relatives, plans for the weekend.

On the other hand, what person ignores commands from officers pointing guns, hits a couple of their cars, and drives on? “We all speculated that she was trying to get her child out of danger, when she was confronted with people with guns, because that’s what she would do,” Nicholson says.

The gunfire — 26 bullets in all — sets the Carey case apart. Shootings by officers on these two forces are rare. White House guards didn’t resort to their weapons in September, when fence-jumper Omar Gonzalez, who had a knife in his pocket, ran far into the executive mansion before being tackled. Carey was unarmed.

“There was no indication she ever had issues,” Nicholson continues. “You couldn’t ask for a more professional person than her. No one ever complained about her, and that’s highly unusual. She was the sweetest person you ever want to know.”

Nicholson looks out the window to the parking lot where Carey used to park the Infiniti. “You could see the [child’s] car seat in the back of that car,” she says.

The leaves are turning gold this afternoon in early October, as they would have been the last time Carey stood at this chair and looked out the window.

After her last patient that Wednesday, Oct. 2, Carey prepared to depart. She usually left by 5 p.m. to pick up her daughter at day care. She lived in Stamford, Conn., 24 miles from Ardsley, 265 miles from Washington.

Her schedule called for her to be off Thursday and Friday, then she was to work at her other dental job in the Bronx on Saturday, and she’d be back here at Advanced Dental of Ardsley on Monday.

“She was absolutely normal,” Nicholson says. “I still remember her standing there, saying, ‘Bye, have a nice weekend. See you on Monday.’ As if nothing.”

There is no public record of her movements or contacts until the following afternoon at 2:13, when she drove up to the Secret Service kiosk at 15th and E streets NW.

“You could see both sides of the story,” Nicholson says. “But I’m sorry. That child does not have a mother because they wanted to handle it their way.”