Orlando Bosch, 84, a Cuban pediatrician turned bazooka-toting militant who plotted to assassinate Fidel Castro and was linked to the 1976 bombing of a Cuban airliner, died April 27 at a hospital in Miami. No cause of death was reported.

To some, Dr. Bosch was a Cuban patriot with a justified cause against Castro’s tyranny. To others, including officials at the U.S. Justice Department, he was a terrorist responsible for the deaths of scores of innocents.

As a student at the University of Havana in the 1940s, Dr. Bosch considered himself a close friend of Castro, a classmate whom he called a “brother.” The pair used to break a cigar in half and smoke the stubs together at all-night cafes.

But after Castro came to power in1959, Dr. Bosch turned against him. He moved to Miami in self-imposed exile and began to scheme to bring down Castro.

His earliest efforts were haphazard at best. He was arrested in 1964 for towing a jerry-built torpedo through downtown Miami during rush hour.

Two years later, police discovered that Dr. Bosch had six 100-pound bombs stuffed in the back of his Cadillac convertible. He later told the authorities that he was taking them “to a secret base where there was a boat we could use to bomb Castro.”

In 1968, Dr. Bosch stood on a bridge over Miami’s Biscayne Bay and fired a homemade bazooka at a Polish freighter.

Despite terrible vision — he wore Coke-bottle glasses — Dr. Bosch managed to hit the ship, but the projectile harmlessly plinked off the metal-plated hull and splashed into the water.

When he was arrested, Dr. Bosch said he attacked the vessel because he thought it was headed for Cuba. He was sentenced to 10 years in prison; he served four and was paroled.

Upon his release, Dr. Bosch fled the United States and spent two years in South America, becoming more bent on upending Castro’s government.

On Oct. 6, 1976, Dr. Bosch allegedly received a phone call from a comrade-in-arms who told him: “A bus with 73 dogs went off a cliff and all got killed.”

The voice on the line had covertly informed Dr. Bosch that a bomb aboard Cubana Airlines Flight 455, bound for Cuba from Guyana, had sent the plane plunging into the ocean. The plane, crashed five miles beyond the coast of Barbados, a refueling stop.

Among the 73 people killed were members of the Cuban national fencing team, several teenagers and a pregnant 23-year-old.

Shortly afterward, Dr. Bosch and three other men were arrested in Venezuela on charges connecting them to the bombing. Jailed for 11 years awaiting trial in Venezuela, Dr. Bosch was acquitted three times and released in 1987. (Two of the arrested men were sentenced to 20 years in prison. The third, Luis Posada Carriles, a onetime CIA operative, escaped from confinement in 1985 and now lives in the United States.)

In 1988, Dr. Bosch returned to Miami and was arrested for violating his parole in the 20-year-old bazooka case.

American authorities immediately tried to deport him. A Justice Department report said that from 1961 to1968, Dr. Bosch was involved in 30 acts of sabotage in the United States, Puerto Rico, Panama and Cuba.

Joe Whitley, who was then the associate U.S. attorney general, said in 1989 that Dr. Bosch had been “resolute and unwavering in his advocacy of terrorist violence” and had repeatedly “demonstrated a willingness to cause indiscriminate injury and death.”

The Justice Department asked 31 countries to take Dr. Bosch. All denied him entry. Another accepted: Cuba.

Dr. Bosch’s lawyers equated the Cuban offer to a death sentence and refused. In 1990, President George H.W. Bush overruled Dr. Bosch’s deportation order, and he remained in Miami for the rest of his life.

Orlando Bosch Avila was born in Potrerillo, a village about 150 miles east of Havana, on Aug. 18, 1926. He was five days younger than Castro.

After graduating from medical school at the University of Havana, Dr. Bosch went to Toledo, Ohio, for his internship and served his pediatric residency in Memphis. He claimed to have been one of the first doctors in Cuba to administer the newly developed polio vaccine, in 1955.

He served as a provincial leader in Castro’s underground movement against dictator Fulgencio Batista before turning against Castro. He said he was trained in guerrilla warfare by the Central Intelligence Agency before the failed Bay of Pigs invasion of 1961.

His first marriage to medical school classmate Myriam Ares, an obstetrician, ended in divorce. Survivors include his second wife, Adriana Delgado Sepulveda Bosch; six children; and five grandchilden.

While in prison, Dr. Bosch took to painting landscapes in his cell. Using cheap brushes, and sometimes a spoon and fork, he composed pastoral scenes of windmills and dikes in Holland and tropical visions of Cuba.

His works sold for high prices in South Florida, especially Little Havana, where Dr. Bosch had a near-mythic reputation.

One morning, at a cafe in Miami, Dr. Bosch’s daughter Myriam was told she didn’t have to pay her bill.

As she told The Post in 1988: “This old man comes up and says, ‘You’re Bosch’s daughter. I’ve already paid. I tell you, I think of Bosch and then I think of my home country and then I just want to cry.’ ”