According to the BBC, officials were not ruling out murder or suicide as the cause of death, and were investigating reports he had received death threats.
Selarón was a familiar face in the Lapa neighborhood of Rio where he lived and worked, and could often be seen adding to the "kaleidoscope stairs" that were transforming the area.
Many of the tiles Selarón used were from old bathtubs or brought to him by friends from their travels.
"We can speak of Lapa before and after Selarón," said Jocimar Batista de Jesus, who lives among the steps and considered himself a friend. "He changed the face of Rio. His death is something brutish, that makes no sense."
"He had no resources, no support from the city," said Jesus. "The neighbors helped as they could. I brought him tiles from my trips, from Spain, Holland, as I traveled. As it grew, people began to contribute, to send him tiles, to bring them to Rio when they came to visit."
When Selarón began decorating the steps in 1990, he turned a dark, dangerous alley into a "tribute to the Brazilian people" that in 2005 was named a City Landmark. Selarón was declared an honorary Carioca, or resident of Rio.
Friends and visitors braved cold and wind to leave flowers and candles on his doorstep in tribute to an artist that used color and beauty to transform his surroundings for all to enjoy.