A Princeton graduate who was convicted of killing his father, a hedge fund manager, after he reduced his son's allowance was sentenced to 30 years to life in prison on Friday.
Prosecutors said he spent that money "on travel, memberships to elite sporting clubs, and other personal expenses."
But starting in 2014, his parents urged him to become more self-sufficient "and incrementally reduced his monthly allowance," prosecutors said.
When they cut his allowance to $300 on Jan. 4, 2015, prosecutors said Gilbert Jr. walked into their Manhattan home and shot his 70-year-old father in the head with a .40-caliber Glock.
He put the gun in his dad's hand before leaving, prosecutors said, apparently to make the shooting look like a suicide.
“Thomas Gilbert, Sr. was a beloved member of his family and business community when his own son murdered him in a cold-blooded killing,” District Attorney Cy Vance said in a statement about the founder of Wainscott Capital Partners. “I hope that the resolution of this case helps his loved ones as they continue to heal from this devastating loss.
"In spite of all his love and generosity, this defendant shot his father at close range in his own apartment in an unconscionable and brutal crime," Vance said in June when Gilbert Jr. was convicted.
Gilbert Jr.'s mother, Shelley Gilbert, and his lawyer argued he was insane at the time of the shooting and should be institutionalized.
"We are definitely going to appeal," Arnold Levine, Gilbert Jr.'s lawyer, told BuzzFeed News. "We are disappointed in the sentence but not necessarily surprised."
“The testimony from the people who actually knew him...show that he met the definition of insanity at the time — the history of psychosis, delusions, paranoid ideation, specifically toward his father," Levine said.
Levine added "the reduction in allowance has nothing to do with it" and that "the father's cash flow itself was bad, he was having financial problems at the time. That was his motivation for cutting the allowance. There was evidence [Gilbert Sr.] asked [Gilbert Jr.'s} permission" to reduce the allowance.
"Tommy stopped calling his mother and asking for money," Levine said.
The jury found Gilbert Jr. guilty of second-degree murder and two counts of criminal possession of a weapon in the second degree.
“The defendant didn’t want to grow up and be an adult,” assistant district attorney Craig Ortner said during the trial, according to the New York Times. “When his father tried to push him along in that direction and cut his allowance, he threw the ultimate tantrum.”