Horrific new details in death of missing 5-year-old Texas boy Samuel Olson

HOUSTON -- A 5-year-old Houston boy was reportedly dead for weeks before he was reported missing, new details reveal.

A search for Samuel Olson led authorities to a Best Western in Jasper, Texas, on Tuesday, where a child's body was found in a plastic box. Samuel's father's girlfriend, Theresa Balboa, has been charged in connection with the case.

The court documents on Balboa's charge provide shocking details about the little boy's death and alleged disappearance.

NOTE: Some details of the case may be disturbing. Viewer discretion is advised.

Samuel's father, Dalton Olson, called police on Thursday, May 27, to report his son missing, just days before the child's sixth birthday. Dalton said Balboa had been babysitting for Samuel since April 30. That has also been confirmed as the last day that Samuel was in school.

Balboa claimed that at about 7:30 a.m. on May 27, Samuel's mother, Sarah Olson, arrived at the home with another man and took the little boy without permission. Sarah, however, provided authorities surveillance video from her home to show she couldn't have taken the child.

While authorities and volunteers with Texas EquuSearch, a search and rescue organization, combed a field looking for signs of Samuel on Monday, authorities now believe the little boy had already been dead for weeks.

Balboa's roommate, Benjamin Rivera, told police that it was about May 10 when Balboa called him to say Samuel was dead. He says he came home to the apartment in the 15600 block of the Gulf Freeway and found Samuel bruised and unresponsive on the bed.

Rivera further told police that he and Balboa put the boy's body in the bathtub and left him there for two days.

On May 13, Rivera says he bought duct tape and a plastic box from a Walmart, and that he and Balboa wrapped up the child's body, placed it in the box and took it to a storage unit on Highway 3 in Webster.

MORE | Body found in TX search for missing boy; father's girlfriend charged

What happened to Samuel Olson? In the video above, we have coverage of what led to criminal charges to what's next in the investigation after a child's body was found in a motel room.

During the search for Samuel on Monday, Balboa reportedly called a friend and told him she needed help because she had been in a fight. The man picked her up in Cleveland, Texas, at a Walmart parking lot. They drove to the storage unit in Webster, picked up a storage container with a foul odor and drove to the Best Western in Jasper, according to court documents.

Following a Crime Stoppers tip call, Jasper police entered the hotel room and found the body they believe to be Samuel in a plastic tote box.

Balboa has been charged with tampering with evidence, in particular a human corpse. She is currently waiting to be brought back to Houston from the Jasper County Jail.

So far, Balboa is the only one who has been arrested in the case of Samuel's death.

Samuel's mother, Sarah, spoke through her attorney about the charges against Balboa.

"Theresa is in custody, but she also strongly believes that the adults, you know, the child's father, should also be in custody, because she feels 100% that they both have something to do with this," attorney Marco Gonzalez said. "So, she's hoping, you know, praying that he also will be taken into custody. So that justice can be done for Samuel."

Police have yet to say anything about a possible motive in the child's death.

TIMELINE: What happened to Samuel Olson?

WATCH: With conflicting information in the case of Samuel Olson's disappearance and death, here's everything we know so far about the timeline of when he was last seen.

WATCH | Mom of Sam Olson says boy's dad, girlfriend are '100%' to blame

"She feels that if Samuel is deceased ... [and] that this is her child after the identification process, she feels 100% of the blame is on both [the father] and Theresa," said attorney Marco Gonzalez.