The Williamson County Sheriff’s Office said that 39-year-old Daniel Logan randomly broke into his neighbour’s home on 11 September and attacked little Jeremy inside.
An arrest affidavit, obtained by the Austin American-Statesman, said that the suspect had managed to enter Jeremy’s house through the back door and made his way upstairs.
There, he found the six-year-old, who he hit in the head, causing multiple fractures to the child’s skull and swelling to the brain.
The suspect also allegedly attacked his own mother, hitting her in the face with the bat after she followed him into the house and begged him to stop.
Mr Logan’s wife told investigators she heard loud banging and saw her mother-in-law emerge from the neighbours’ home covered in blood.
She said her mother-in-law “frantically screamed that Daniel was killing everyone inside,” and asked her call 911, the affidavit states.
Deputies responded to the scene in Georgetown, Texas, at around 5am that morning and arrested Mr Logan.
He was charged with aggravated assault and injuring a child with a deadly weapon.
He has been ordered to undergo a competency evaluation.
Little Jeremy was taken to hospital where his family said he is still “fighting for his life”.
In a GoFundMe launched to cover his medical bills and potential legal expenses, the family wrote: “Jeremy remains in critical care, but he continues to show movement in all his limbs and is responding.”
The six-year-old was described as “a bright, vibrant child with a heart full of dreams and a future brimming with potential” who was looking forward to dressing up as Iron Man for Halloween.
“His innocent smile has been replaced with pain and suffering, but we refuse to let him face this battle alone,” the fundraiser reads.
The GoFundMe has so far raised more than $200,000.