Authorities say 18-month-old Zachary Tendoy was killed in Idaho last month after being allegedly beaten by his mom's boyfriend
Credit: GoFundMe

Authorities say an 18-month-old boy was killed in Idaho last month after sustaining skull fractures, brain swelling, torn blood vessels and retinal hemorrhaging in his eyes.

His mother’s 22-year-old boyfriend remains behind bars, accused of viciously beating the little boy.

Zachary Tendoy was a “very happy and light-spirited” child, according to those who knew him. But his last moments were anything but: Doctors who examined the battered toddler told police that his injuries were comparable to a high-speed car crash, court records show.

After he was charged in Zachary’s death, Jesus Adan Castillo allegedly told investigators he’d been drinking for hours before lashing out at the child for “whining” and “bothering him,” according to the court documents.

Here are five things you need to know about the case.

1. Castillo Claimed Zachary Fell from His Crib: Records

Castillo has been charged with murder, aggravated battery and injury to child in Zachary’s death and is being held at the Bingham County Jail in Idaho on a $1 million bond.

His attorney was unavailable for comment on Thursday. He has yet to plea to the charges against him and is scheduled to be arraigned on Monday.

He initially called 911 on March 23 claiming the boy had fallen out of his crib while he was showering and the boy’s mother was asleep, court records show.

Castillo allegedly told police he had been drinking with the boy’s mother but decided to take a shower after she went to bed.

While in the bathroom, he allegedly said he heard a thud and found that Zachary had crawled out of his crib, according to the court documents, which were obtained by PEOPLE. He allegedly said that he returned the child to his crib and gave him a bottle.

2. Suspect Later Allegedly Confessed

Under questioning by police, Castillo eventually admitted that he began to attack Zachary once his mother was asleep after becoming upset by the boy’s behavior, the court records claim.

When Zachary left his crib a second time, Castillo allegedly said that he pushed the boy “as hard as he could” because the boy began “whining.” He fell into a door jamb but continued to follow Castillo.

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The suspect allegedly said Zachary was “bothering him,” so he kicked the toddler in the torso before shaking him over and over, court records state.

Authorities arrived to the home to find Zachary unresponsive on his back.

Jesus Adan Castillo
| Credit: Blackfoot Police

3. Victim Organs Were Donated

The day after he was transported to a local hospital for treatment, doctors determined Zachary was brain dead.

A CT scan had revealed he suffered multiple skull fractures on both sides of his head, and police documents allege he had brain swelling.

Doctors also determined Zachary had tears in his major blood vessels and valves as well as retinal hemorrhaging in his eyes. They told investigators that such injuries were comparable to those sustained in a 70-mph car crash, court records show.

Any attack that inflicted such trauma was “very violent,” the doctors said.

Police say Zachary’s parents agreed to donate his organs, which eight children received.

4. Suspect Has a Child of His Own

Court records show that Castillo is, himself, a father.

He filed for divorce from his ex-wife in late 2015 and a brief custody battle followed over their child, court records show.

He was granted a divorce in early 2016.

5. Victim’s Family Is Devastated

Zachary’s relatives have done their best to avoid the media in the wake of the toddler’s death. But his godmother, Bianey Osuna, tells PEOPLE they are having difficulty coping.

“This is hard enough for us as it is,” Osuna says, noting news reports of the murder have been “making it that much harder for us” to heal.

Osuna described her godson in a GoFundMe campaign as “very happy and light-spirited.”

“He loved to smile and laugh,” she wrote of Zachary. “He loved to sing and dance to anything he could hear.”

She reportedly said in March that Zachary’s mother was “not doing well.”

“I have talked to her every day since this happened,” Osuna said. “She really isn’t doing well, but she is staying strong for her other child.”