An Aer Lingus flight from Lisbon to Dublin was diverted to an alternate airport on Sunday after a Brazilian man traveling on the plane collapsed and died moments after he had bitten a fellow passenger.

Once on the ground, meanwhile, authorities discovered that a Portuguese woman accompanying the deceased was carrying five pounds of suspected amphetamine powder in her suitcase, police in the southwestern Irish city of Cork said, according to Fox News.

According to the Irish Times, the man has been identified as John Kennedy Santos Gurjao. The cause of death, as determined by the medical examiner, was cocaine overdose after one of the pellets he was carrying in his stomach burst. The examiner found around 0.8kg of cocaine in 80 wrapped pellets. 

The 24-year-old Brazilian man had initially been restrained by fellow passengers, John Leonard, one of those traveling on the flight, told a local radio station. "After that it got worse I would say, his seizure seemed to get worse. He was actually on the ground shaking violently," Leonard said.

"The noise he was making was like something I have never heard before. It's not something you'd hear every day. It was like deep anguish, is the best way I could describe it. Very, very troubled. Not screaming in a sense you know if you'd hurt yourself or something, just a very guttural, from deep within him," the witness added.

An unidentified technology worker also on the Aer Lingus flight, meanwhile, told the Daily Mail that he had been sitting next to the man for much of the flight and he had seemed normal at first.

"He seemed OK," the source noted. But later into the flight, he "began shaking and shivering, but I just thought it might have been cramp or something. ... I got past him and went to see one of the flight attendants to tell them I thought he might be having a seizure. Then he just jumped up from his seat and ran across the arm rests and pushed the food trolley out of the way and went to the back of the plane," the fellow passenger added.

A postmortem exam was conducted on the man's body on Monday, and his fellow traveler, a 44-year-old Portuguese national, remains in custody, the Associated Press reported. The remaining 165 passengers and six crew members, meanwhile, traveled by bus to Dublin, the flight's original destination, according to the newswire.