A Prince William County mother of three, whose toddler son died last month after he was left in the family’s minivan for about seven hours, was indicted Tuesday on charges of felony murder and child neglect.

Karen Murphy, 40, of Gentle Shade Drive in the Bristow area, allegedly left her son, Ryan, who was just shy of his third birthday, strapped in his car seat when she went to work on the morning of June 17. After leaving her job as a veterinarian that afternoon, authorities said, she drove home. Her husband went to pick up Ryan from day care, then called his wife, saying their son was not there.

Murphy then discovered Ryan, unresponsive, in the minivan parked in the driveway, Prince William police said. Her screams could be heard throughout the neighborhood.

Though not particularly hot that day — temperatures were in the 70s and low 80s in the region — cars parked outside can heat up quickly and become stifling and deadly, especially for children. Prince William police and prosecutors said the boy was probably in the minivan for seven hours or more.

Prince William Commonwealth’s Attorney Paul B. Ebert, who has pursued cases in which children were forgotten in cars, said Murphy left her son in the vehicle accidentally but that her actions and inactions rose to the level of crimes.

He said his decision to present the case to a grand jury was based in part on allegations that Murphy had forgotten Ryan in January when the minivan was parked outside her veterinary office, Caring Hands Animal Hospital. In that case, he said, day-care employees called her to ask whether Ryan would be coming, and she took him from the vehicle after less than a half-hour.

“It certainly wasn’t intentional,” Ebert said. “But the fact is that she was on notice. This is an innocent child, and she wasn’t up to speed on taking care of him. It gets to the point where it becomes neglect.”

Murphy’s attorney, Edward B. MacMahon Jr., said Murphy planned to turn herself in Wednesday morning at a court appearance in Prince William. MacMahon said she has two other children, both preteen girls, and that Ryan’s death has been a shock to the family.

“It’s obviously a tragedy,” MacMahon said. “She’s a wonderful woman, she’s a wonderful mother, and this is just a tragedy that has devastated her. It’s so sad.”

Law enforcement officials said that Murphy usually took Ryan to a day-care center near her clinic and that she left her home at 8:45 a.m. June 17 with the toddler before her husband had left the house. The boy wasn’t removed from his car seat until about 4 p.m., when the minivan was back in the family’s driveway.

A charge of felony murder in Virginia alleges the unintentional killing of another person in the commission of a felony, which in this case is child neglect. If convicted of felony murder, Murphy would face a maximum sentence of 40 years in prison.

MacMahon, who declined to discuss the facts of the case, said the charges are the “most drastic” that could have been brought, adding that some similar cases have resulted in misdemeanors. Murphy was indicted just 18 days after her son’s death and will be appearing in court 10 days before what would have been his third birthday.

In about 60 percent of similar cases nationwide, authorities have alleged a caretaker was negligent and filed felony charges, according to a child safety advocacy group. In the remainder of the cases, authorities deemed the deaths terrible mistakes that were not criminal.

In a high-profile case in Manassas, Ebert’s office charged Kevin C. Kelly with involuntary manslaughter after he left his youngest daughter in a van in May 2002 for seven hours, resulting in the death of 21-month-old Frances Kelly. Convicted by a jury, Kelly was sentenced in February 2003 and received one day in jail every year for seven years, and a judge ordered him to do community service around the date of his daughter’s birthday.