Law enforcement officers were called to the scene in Harvey County on Thursday night after Lucas' 27-year-old stepmother, Emily Glass, led a private investigator to the remains near the town of Sedgwick, about 20 miles (32 kilometers) north of Wichita, Wichita Police Chief Gordon Ramsay said at a news conference.
The investigator, David Marshburn, called police about the body and officers met him and Glass at the scene. Marshburn said he was hired by the boy's father. He told police he arrived in Wichita from Smithfield, North Carolina, this week, Ramsay said.
Pressed as to how Marshburn was able to locate the body so quickly when police have been searching unsuccessfully for months, Ramsay would only say that police are bound by "very strict rules" that do not apply to private citizens.
Marshburn, who owns Marshburn's Investigation Agency, told The Associated Press in a phone interview as he was driving back to North Carolina that he spent less than 11 hours with Glass before finding the body.
Law enforcement officials have to consider a suspect's constitutional rights - such as reading them their Miranda rights against self-incrimination - and all that is intimidating to somebody, Marshburn said, adding that he and his assistant, Marsha Ward, actually use "lesser aggressive tactics toward people" than police.
"I just call it being nice, I call it being civil. It's just the way I do things," Marshburn said. "It's hard to describe and it's hard to say ... I am not gonna to spill the secret of how we do it."
Marshburn declined to talk about Glass' reaction at the scene for fear of jeopardizing the prosecution's case. He also refused to say whether Glass had told him what happened to the boy.
He said it took him and Ward about four hours to actually find the body after they got to the general area, and had to work off clues rather than go right to it. They drove around with Glass as they talked and looked, he said.
"All those roads look alike, all those bridges look the same, all those woods - everything just looks the same. And then you go from winter to summer, I mean things just change, and you are dealing with a person whose mind is not even clear all the time," Marshburn said. "We had to do it step by step."
Glass was jailed Thursday on suspicion of felony obstruction of justice, but no charges are expected to be filed this week.
Sedgwick County District Attorney Marc Bennett said in an email Friday that his office will review early next week the results of the autopsy, as well as evidence gathered by law enforcement throughout this investigation.
When asked if other arrests are possible, Ramsay said only that the investigation is still "very active."
Glass reported Lucas missing from their home on Feb. 17. Glass told police she last saw Lucas playing in his bedroom before she took a shower and fell asleep. He was gone when she woke up from her nap. She has not been charged in the boy's disappearance, but Bennett previously said she is a person of interest in the case.
The boy's father, Jonathan Hernandez, was not at home when Lucas disappeared. Glass cared for her daughter and Lucas while he worked out of state for weeks at a time. Lucas' biological mother didn't live in the Wichita area when he disappeared.
Glass was found not guilty in May in an unrelated case accusing her of child endangerment involving her 1-year-old daughter. Prosecutors alleged she smoked marijuana before driving the child to a restaurant.
Lucas was reported missing the day after that trip.
A court document related to that case said Lucas was frequently seen with bruises and cuts before he disappeared. The Sedgwick County juvenile court document indicated the state of Kansas was told at least twice that Lucas was being abused and was living in a dysfunctional and violent situation.
This story has been corrected to show the district attorney's name is Marc Bennett, not Mark.
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