Accused daddy killer Thomas Gilbert Jr., whose lawyers have mounted an insanity defense, searched for contract killers and hit men on the internet in the months before he allegedly shot his millionaire hedge-funder father in the head.

Prosecutors unveiled Gilbert Jr.’s browser history in Manhattan Supreme Court on Monday, with the clueless 34-year-old trawling the internet for “hit man forum,” “murder for hire” and “searching for a hit man in the deep web” in October 2014.

The bratty Princeton graduate, 34, is on trial for the murder of his father, Thomas Gilbert Sr., who was shot on Jan. 4, 2015, after slashing his son’s weekly allowance by $100.

Prosecutors told jurors that the following terms were listed on his browser search history for Oct. 5, 2014:

“Hit man forum”

“Murder for hire”

“Contract killing”

“Hire-a-killer.com”

“Searching for a hit man in the deep web”

“Apparently hiring an actual hit man is more difficult than the Dread Pirate Roberts imagined”

“Silk Road”

“Hitman Network”

And email exchanges presented in court show the fragile ego and coddled existence Gilbert Jr. led — ungraciously giving his father financial advice while living entirely off his old man’s purse.

The handsome former surfer was a fixture on Manhattan’s black-tie society circuit while his parents footed the bill, covering the $2,400 rent for his West 18th Street apartment and $600 spending money each month.

In one email exchange from March 2014, Gilbert Jr. asks his father for $250 for clothes before telling daddy who he was living off to stop contacting him several weeks later.

“Again, I requested no emails,” wrote Gilbert Jr. after his hedge fund father sent him a series of emails that were attempts to help Jr. get off the ground.

“Please stop so I don’t have to change my email address,” Gilbert Jr. continued. “This is a form of harassment.”

Emails and voicemails presented in court shows Gilbert Jr. was coddled by his folks, who referred to him as “Tommy.” His mother and lawyers both argue he is mentally unwell.

In one email, Gilbert Jr.’s mother chastised him for not using frequent flyer miles when he traveled.

In another instance, Gilbert Sr. meekly asked if he could lower his party boy son’s allowance.

“Is it alright with you if I lower your weekly allowance from 800 to 600?” he wrote.

Gilbert Jr.’s attorneys have mounted an insanity defense, arguing his client has a long history of mental illness, including schizophrenia.

Prosecutors argue Gilbert knew exactly what he was doing when he shot his dad in the head with a .40-caliber Glock and fled.

Mother Shelly Gilbert is the prosecution’s star witness, testifying against her son, and told The Post she’d been trying to get her mentally unwell son into a hospital for 15 years.

“He doesn’t belong in jail, he belongs in a hospital,” she said “It’s what my husband would have wanted for him if he was still here.”