MANASSAS, Va. (AP) -- What is the appropriate punishment for a doting parent responsible for his child's death?

Kevin Kelly is a law-abiding citizen who, much distracted, left his beloved 21-month-old daughter in a sweltering van for seven hours.
Frances Kelly had probably been dead for more than four hours by the time a neighbor noticed her strapped in her car seat; when rescue personnel removed the girl from the vehicle, her skin was red and blistered, her fine, carrot-colored hair matted with sweat. Two hours later, her body temperature was still nearly 106 degrees.
A judge eventually spared Kelly a lengthy term in prison. Still, it is a question that is asked dozens of times each year.
Since the mid-1990s, the number of children who died of heat exhaustion while trapped inside vehicles has risen dramatically, totaling around 340 in the past 10 years. Ironically, one reason was a change parent-drivers made to protect their kids after juvenile air-bag deaths peaked in 1995 — they put them in the back seat, where they are more easily forgotten.
An Associated Press analysis of more than 310 fatal incidents in the past 10 years found that prosecutions and penalties vary widely, depending in many cases on where the death occurred and who left the child to die — parent or caregiver, mother or father:
Mothers are treated much more harshly than fathers. While mothers and fathers are charged and convicted at about the same rates, moms are 26 percent more likely to do time. And their median sentence is two years longer than the terms received by dads.
Day care workers and other paid baby sitters are more likely than parents to be charged and convicted. But they are jailed less frequently than parents, and for less than half the time.
Charges are filed in half of all cases — even when a child was left unintentionally.
In all, the AP analyzed 339 fatalities involving more than 350 responsible parties. July is by far the deadliest month, accounting for nearly a quarter of the total.
A relatively small number of cases — about 7 percent — involved drugs or alcohol. In a few instances, the responsible parties had a history of abusing or neglecting children. Still others were single parents unable to find or afford day care.
Many cases involved what might be called community pillars: dentists and nurses; ministers and college professors; a concert violinist; a member of a county social services board; a NASA engineer. And it is undisputed that none — or almost none — intended to harm these children.
""When you look at overall who this is happening to, it's some very, very, very good parents — might I say, doting parents,"" says Janette Fennell, founder and president of Kids and Cars, a nonprofit group that tracks child deaths and injuries in and around automobiles.
""But no one thinks it's going to happen to them. I think people are lying if they say that there wasn't one situation in raising their child that, `There but for the grace of God go I.'""
The AP's analysis was based largely on a database of fatal hyperthermia cases compiled by Fennell's organization. The AP contacted medical examiner's offices in several states where this most often occurs, and the group's numbers coincided almost exactly with recorded hyperthermia deaths.
Some of these children crawled into cars or trunks on their own, but most were left to die by a caregiver. Most often, it was a parent who simply forgot the child was inside.
Texas leads the nation with at least 41 deaths, followed by Florida with 37, California with 32, North Carolina and Arizona with 14 apiece, and Tennessee with 13. There were deaths recorded in 44 states — most in the Sun Belt, but many in places not known for hot weather.
The correlation between the rise in these deaths and the 1990s move to put children in the back seat is striking.
""Up to that time, the average number of children dying of hyperthermia in the United States was about 11 a year,"" says Jan Null, an adjunct professor of meteorology at San Francisco State University who has studied this trend. ""Then we put them in the back, turned the car seats around. And from '98 to 2006, that number is 36 a year.""
Few understand just how quickly a car can heat up, even on a moderate day.
According to one study, the temperature inside a vehicle can rise more than 40 degrees in the span of an hour, with 80 percent of that increase occurring during the first half hour. And researchers found that cracking the windows did little to help.
Children, often too young to escape, are particularly vulnerable because their immature respiratory and circulatory systems do not manage heat as efficiently as adults'. After a short time, the skin grows red and dry, the body becomes unable to produce sweat, and heat stroke kills the child.
Already this year, at least 16 children have died in hot vehicles from Hawaii to Virginia — including a 4-year-old New Orleans boy who died on Father's Day