The Ohio woman who found the bodies of two missing New Hampshire children said Monday she had been searching with her dog for months on a personal mission that her friends and family considered an obsession.

Stephanie Dietrich, a grocery store cashier, said she was motivated to look for Sarah Gehring, 14, and her brother Philip, 11, by their mother's public plea for help.

The children's father, Manuel Gehring, shot them to death in 2003 and told authorities he buried the bodies somewhere along a 700-mile stretch of Interstate 80 across the Midwest. He gave investigators several details about the spot but said he could not remember the location, then committed suicide in jail before a trial.

Dietrich, 44, said she went out searching with her dog more than 40 times since July near her Akron home because of clues suggesting the gravesite could be in the region. Investigators had concluded in 2004 that pollen found on dirt on Gehring's minivan and shovel suggested that the soil most likely came from northeastern Ohio.

Last Thursday, Dietrich was looking in the well-to-do suburb of Hudson for things like tall grass, sewer pipes and a wood pile that the father described when her 101-pound mixed breed dog, Ricco, stopped in the woods and "just laid down and started looking at me."

Dietrich said she saw a small mound with twigs covering it. She started digging, came upon a plastic bag and pulled out what appeared to be part of a cross made of willow twigs and duct tape. She called police on her cell phone, and the children's bodies were removed from a shallow grave.

Dietrich said she kept a 2-inch-thick folder of news articles and tips from the Internet and often woke up in the middle of the night to read it.

"It was like a personal challenge. Not like it was a game. I knew it was serious," she said. "My family members and friends were like ready to have an intervention because I was obsessed with it."

In New Hampshire, a prosecutor said Monday that he believes Gehring deliberately misled investigators about the burial site. The details Gehring gave ultimately proved accurate with last week's discovery. But when Gehring rode along with investigators for days in a search for the spot, he failed to lead them to the site.

"He clearly led them away from the actual location," Senior Assistant Attorney Jeff Strelzin said. He added: "Having seen the violence he inflicted on his children, it was pretty obvious he didn't want the public or the prosecution to be able to use that information against him."

Jackie Colburn, one of Gehring's public defenders, disputed that notion, saying that even the investigators traveling with Gehring reported that one exit looked like another along the highway.

"If his goal were to mislead them, why would he give them the level of detail, and the level of accurate detail?" she said.