MIAMI BEACH — When Israel Hernandez Bandera, a former airline pilot, came to the United States from Colombia eight years ago with his wife and two children after being granted political asylum, he was deeply grateful to the country that shielded him from the guerrillas who had extorted money from him and threatened to appropriate his family’s land.

Now, in the wake of the death of his 18-year-old son, who was chased down by Miami Beach police officers early Tuesday and collapsed after one of them shocked him with a Taser, Mr. Hernandez Bandera and his family are having doubts about justice in his adopted country.

“I believe in the United States,” he told reporters outside his home. “I am proud to be here. But this government should not support these acts.”

The death of the son, Israel Hernandez-Llach, an accomplished artist known as Reefa who the police say had been marking an abandoned building with graffiti when he was pursued, has become the focal point of protests calling for independent investigations into the officers’ conduct. Many of the protesters point out that Miami Beach police officers have been the subject of repeated complaints of excessive force in the past.