The prosecutor said the case first began May 1, 2017, when paramedics were called to the home in Osgood where the then-13-year-old Kedrowitz; his mother, Christina McCartney; his stepfather, Steven Ritz; and three younger siblings lived. When they arrived, they found Desiree was not breathing.
The Batesville Herald-Tribune reported that McCartney told investigators when she arrived home from work, she found Kedrowitz holding Desiree in a towel.
"Christina said Nickalas told her that he did not think Desiree was feeling good because she was not talking to him," investigators wrote in a probable cause affidavit Hertel provided to reporters at Wednesday's news conference.
McCartney began CPR while Ritz called 911, the court document said.
Desiree was taken to Margaret Mary Health in Batesville before being transferred to Cincinnati Children's Hospital, where she died five days later, Hertel said Wednesday.
State police investigators started looking into the toddler's death, as did child welfare workers with the Indiana Department of Child Services. According to the Herald-Tribune, Ritz told detectives that he was bathing Desiree when Nathaniel, then 8 months old, and another child, 1-year-old Abby, began crying in another room.
Ritz said he left Desiree in the tub for a few minutes, with Kedrowitz watching over her. When he returned, she was not breathing. The teen told investigators he left her alone for a minute to retrieve some baby wipes, the Herald-Tribune reported.
Both investigations into Desiree's death were still ongoing July 20, 2017, when paramedics were again called to the family's home, where they found Nathaniel unresponsive, Hertel said Wednesday. The boy, like his sister, was taken to Margaret Mary Health, where he was pronounced dead early the next morning.
McCartney told investigators she'd asked Kedrowitz to tuck Nathaniel into bed, the affidavit said. A few minutes later, the teen told his mother, "Something is not right with Nathaniel. He is not acting right," the court document said.
A second detective began investigating Nathaniel's death, though he and the investigator in Desiree's death coordinated their efforts, since both deaths occurred in the same household, Hertel said during the news conference.
The investigations, which were already focused on the people living in the household, soon began to focus more sharply on Kedrowitz, Hertel said.
"The police officers start getting some information that's contained in the probable cause affidavit about some rather disturbing statements that the 13-year-old was making to a variety of different individuals," the prosecutor said.
The probable cause affidavit indicated that multiple people told investigators that Kedrowitz had talked about "some things (he) had done to some kittens," Fox59 in Indianapolis reported.
That included mutilating a kitten "to the point of almost killing it" at his great-aunt and great-uncle's home, the news station reported. The great-aunt, who has diabetes and a prosthetic leg, told investigators Kedrowitz told her "with all of her health problems, maybe she just needed to die."
Kedrowitz made similar statements about an old dog at the home, the court document said.
Kedrowitz's great-aunt told investigators that the teen mutilated some of her kittens, one so badly that its internal organs were hanging out and it was covered in blood, the Herald-Tribune said.
Kedrowitz admitted to his great-aunt that he got angry when the kitten scratched him and "squeezed (it) really hard," the newspaper said. When his great-uncle realized the cat needed to be destroyed, Kedrowitz asked if he could go see "the kitten's brains splattered everywhere," the court document said.
State police investigators questioned the teen Dec. 13, 2017.
"Nickalas then began to tell us about some dreams he had after (Desiree and Nathaniel) had died," the affidavit said, according to the Herald-Tribune. "Nickalas started talking about saving Desiree and Nathaniel from hell and the chains of fire. Nickalas said he had help from an angel to free them."
When asked what hell was to him, Kedrowitz replied, “Chores,” the affidavit said.
The detectives asked how the toddlers died. Kedrowitz told them he put a towel over Desiree's head in the bathroom to "set her free to heaven," the document said. Investigators said he also admitted that he put a blanket over Nathaniel's head.
The Herald-Tribune reported that, although the cause of the children's deaths was undetermined, the coroners who conducted the examinations have since amended their reports to say both were smothered to death.
Hertel said Wednesday that the judge presiding over Kedrowitz's first court hearing on Monday ordered a competency evaluation for the teen.
"This child will be evaluated by two doctors," Hertel said. "They will give reports to the court and the court will make a determination whether he's competent to stand trial."
In Indiana, competency means the defendant understands the proceedings going on around him and can assist in his defense, the prosecutor said.
Monday’s court hearing was also when Hertel’s office filed a motion to waive Kedrowitz to adult court.
"He (was) 13 years old, obviously very young," Hertel said. "However, I want to point to a part of the documents that were provided to you."
He explained that the waiver would be a presumptive waiver, meaning it could be granted if certain conditions are met.
"Those conditions are he's been charged with murder," Hertel said, ticking off the conditions on his hand. "That there's probable cause he committed murder and that he was at least 12 years of age."
A juvenile defendant could be kept in the juvenile court system, however, if it is in the best interest of the child and in the safety and welfare of the community.
"The state believes that, given the information provided by the investigation, by these gentlemen behind me, the probable cause that you all have, his age being 13, that a petition to waive is appropriate in this matter," Hertel said. "Ultimately, the judge will make that determination."
The prosecutor said he’s never charged a child so young with murder before. He said that McCartney and Ritz have been cooperative with the investigation, but he has not ruled out the possibility of them facing charges.
“Whether they were negligent or should have done something, I don’t know if it rises to the level of criminal conduct,” Hertel said.
McCartney told Fox19 in Cincinnati that she believes abuse by Ritz caused her son to lash out at his younger siblings.
"He witnessed him being mean to the babies," McCartney told the news station. "That he pushed them down on purpose. He would lock them up in the bedroom to try to shut them up. He painted a pretty bad picture. As a mom that's hard to swallow that was going on and I didn't know."
She said she believes Kedrowitz may have been ordered by Ritz to kill the toddlers. She called the teen “every mom’s dream child” and said he adored his younger brother and sisters.
"He's not the monster that people are trying to portray him as," McCartney said. "It's a mother's worst nightmare to have such a precious family and then to wake up to the worst possible outcomes."