It's been a year since Miriam Carey was shot dead by Secret Service agents outside the Capitol, and as the Washington Post points out in a new investigation into the incident, many aspects of her death still make no sense.

Carey, a 34-year-old dental hygienist from Connecticut, was shot to death by Secret Service and Capitol police on Oct. 3, 2013 after she made a U-turn at a White House checkpoint.

According to police and witness accounts, Carey was in a two-door Infiniti with her one-year-old daughter when she drove into a restricted area near the White House. A plainclothes officer tried to erect a portable barrier to prevent her from exiting back out onto the public roadway, and she forced her way past him, launching the police chase.

At the time, reports indicated she had tried to ram through the White House barriers, something the Post says never happened.

She ended up on Pennsylvania Avenue NW, a public road that leads directly to the U.S. Capitol. Here the official U.S. Attorney's report appears to diverge from the established facts—despite claims that she had led police on a "high-speed chase," she was actually only driving an average of 19.5 miles per hour the Post estimates.

When she arrived at the Capitol, the cop cars tried to block her in. Twenty-six shots were fired, and she was hit five times. Her daughter, who was in the backseat of the car, was not injured in the incident.

But it's still unclear how Carey—a woman with a loving family, a child, and a stable job—ended up in a car chase with federal agents through downtown D.C.

Although various theories were floated at the time—post-partum depression and delusional beliefs chief among them—Carey's family and friends have pointed out she didn't seem to have any trouble holding down a job or taking care of her daughter.

"There was no indication she ever had issues," Carey's former boss, office manager Barbara Nicholson told the Post. "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."

Her sister suggests she may have been frightened by the off-duty officer, who did not identify himself when he began to erect a barrier around her, but her family also spoke of delusions she may have had about Barack Obama about nine months before her death.

Also unclear is why Secret Service agents felt compelled to use deadly force against an unarmed woman whose only apparent crime was dangerous driving.

The Secret Service, notably, did not resort to force when Omar Jose Gonzalez jumped the White House fence and ran into the Oval Office with a knife last year. Nor did they fire at Kevin Carr—a 19-year-old who claimed to communicate telepathically with Obama—after he drove past a White House security checkpoint last September, or Mathew Goldstein, who followed the Obama daughter's motorcade into a secure area last May.

In fact, the only other recently documented Secret Service shooting occurred earlier this month, when an off-duty agent witnessed a man robbing a Virginia Walmart with a hammer.

Still, the agents were cleared in an excessive force investigation conducted by U.S. Attorney Ronald C. Machen Jr., the Post reports. The department refused to comment to the Post due to a pending $150 million wrongful death suit filed by Carey's family.

[h/t the Washington Post, image via AP]