Cook's case has also been controversial because just four years earlier she had a dramatic drunken-driving arrest, the bare bones of which top diocesan officials knew when they selected her as a candidate but which they did not share with the broader body that voted to appoint her.

She became the diocese's first female bishop last fall -- a couple of days after Sutton told Katharine Jefferts Schori, head of the entire Episcopal denomination, that he thought Cook might be drunk at a dinner celebrating her own consecration.

The presence of the 59-year-old bishop, the diocese's No. 2 priest, in court Thursday revived the question that has been asked since the day of the crash: How could a prominent member of the clergy hit a man and drive away?

"It's something people don't think they would do, they can't imagine themselves doing it, but the numbers suggest something else," said Lindsay S. Arnold, a research analyst with the AAA Foundation for Traffic Safety.

Yet data shows leaving the scene of a serious injury is not rare. The Insurance Institute for Highway Safety says about a fifth of pedestrians killed by cars in the United States involve drivers who left.

With pedestrian fatalities increasing as a proportion of traffic-related deaths, even as traffic deaths overall go down, experts are delving more deeply into the causes and circumstances behind hit and runs, revealing the complicated, split-second ethical choices drivers make.

For example, research shows drivers are less likely to leave a pedestrian who is under 11 years old or over 66 -- suggesting a calculation and empathy.

Research also shows that drivers are more likely to flee scenes if they can-- if the area is remote or if it doesn't appear there are witnesses. Prosecutors say Cook left the scene after the 2:30 p.m. crash.

Bishop Eugene Sutton, head of the diocese, later said in a statement that Cook returned to the scene "after about 20 minutes to take responsibility for her actions." However, cyclists on several Baltimore news and biking sites said that Cook returned only after cyclists chased her car.

The diocese later put out a different timeline that said she left the scene "for approximately 30 minutes."

Hit-and-run rates vary widely from country to country, though data isn't kept in a uniform way. In the United States, hit-and-run incidents accounted for 20 percent of pedestrian fatalities, compared with 7.7 percent of pedestrian crashes in Ghana (fatal and non-fatal) and 1.8 percent of all crashes in Singapore (not just those involving fatalities and pedestrians), according to Richard Tay, a transportation researcher at RMIT University in Melbourne.

Prosecutors and defense attorneys who handle cases like Cook's note people who risk extra punishment are more likely to leave the scene of an accident -- such as people with a high blood-alcohol level or an invalid license (four times more likely to leave the scene in both cases than drivers in general). But there also remains a basic flight instinct in some cases, attorneys say.

"There is a certain part of you that says: 'Is it bad enough for me to stop?' Your rational mind says: 'You idiot.' But there is that certain flight thing that goes off. I'm surprised so many people indulge it," said John Soroka, a former assistant U.S. attorney in Washington who handled vehicular homicides until 2011.

Soroka said fleeing the scene is in a sense separate from the crime of hitting the person. If someone is drunk and hits someone, "flight may be an indication or knowledge of guilt, but it doesn't change that the crime already happened."

It's not clear if Cook's status as a priest will impact her case. Some experts said the fact that a defendant serves in a position of authority can cut both ways for juries. In the days after her arrest some church officials suggested she was under a lot of stress in her new position.

Being clergy was a powerful aspect in the Wisconsin trial of Bruce Burnside, who last summer was sent to prison for a decade for a case similar to Cook's -- he was intoxicated, texting and left the scene after hitting and killing Maureen Mengelt in 2012. Burnside was a Lutheran bishop who initially denied he'd been drinking and seemed to suggest he didn't realize he'd been involved in a serious crash -- even though his car sustained heavy damage, according to a complaint.

"Why would a supposed man of the cloth commit such a horrible act, and even worse, deny every bit of it? " Mengelt's daughter, Megan, told the court at sentencing. "But I won't accept it..He's not a true man and not a true man of God."

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