Goldman Sachs analyst John Castic may have died from peanut allergy: dad

The Goldman Sachs analyst who was found dead in a creek after attending a concert at Brooklyn Mirage may have died of a peanut allergy, his father has claimed.

John Castic’s father said he believes that his son suffered an allergic reaction after leaving the concert venue in Bushwick around 3:15 a.m. Saturday.

“We think he either had an allergic reaction — he was allergic to peanuts and maybe ate something without realizing that it contained peanuts — or there was an undetected allergy mixed with alcohol,” Jeff Castic told the Daily Mail Wednesday.

The grieving dad said that his son had told his friends that he was not feeling well before deciding to leave by himself.

​“He was at the club and he started to catch ill so he said to his friends that he was going home,” he said.

His son was captured on surveillance video walking calmly along Stewart Avenue from the venue, not far from where his body was recovered in Newtown Creek on Tuesday.

But the family said they’ve been given no indication that foul play was involved in his death.

“All of his personal effects were in his possession, where they should have been, so there was no robbery. So far it doesn’t look like foul play,” he said.

The family is waiting for the medical examiner to determine the cause of death, Jeff told the news outlet.

He described John, who lived in Lower Manhattan, as a “bright, charismatic young man” who “had lots of friends and loved to travel” — adding that he was “very happy” and doing well at work before his tragic death.

The Goldman Sachs analyst’s body was recovered after a man noticed a bloated, shirtless body floating in the English Kills, a branch of the East River tributary, near 1100 Grand St. 

Police sources have said he had no obvious signs of trauma, apart from drowning.

John was the second young man to have disappeared near the Brooklyn Mirage recently and was then found dead in the same creek.

The body of Karl Clemente, also 27, was recovered a few days after he was turned away from the club, sources have said. Sources said his death did not appear to be suspicious.

Meanwhile, Karl’s dad, Alexander Clemente, noted that there’s “so much similarity” between his son’s case and that of Castic – and wondered why it took another young man to end up dead in the creek before the world took notice.

“When you lose one person in such circumstances, it’s too much. If you lose a second person, it’s unbearable. Why did we wait?” Clemente, 65, told The Post on Wednesday.

Police sources have said authorities don’t think the two cases are related. Instead, police are treating them like an unfortunate coincidence, the sources added.