Euclides Monteiro, 40, was killed four years ago in a tractor crash, three years after Madeleine, 3, vanished from her parents' holiday apartment at the Ocean Club in Praia da Luz. Monteiro lost his job as a waiter at the Ocean Club in 2006 because he was suspected of theft, the Daily Mirror reported.
Sergio Paulo, a 44-year-old construction worker in Lagos, the town where Monteiro lived near Praia da Luz, told The Mirror he did not believe his friend would have kidnapped and killed a child. But he conceded Monteiro had problems.
"Toni was a good guy but had some serious drug problems. He would smoke heroin and became a slave to it," Paulo said. "I know he would sometimes break into apartments and rob them. He was taking valuables from rooms at Ocean Club and selling them for drugs."
Portuguese investigators have suggested Monteiro might have kidnapped and killed Madeleine as a way of striking out at the Ocean Club for firing him or that she might have disturbed him while he was burgling the apartment.
Monteiro's wife Luisa said she had been questioned by Portuguese police. She flatly denied her late husband was the kidnapper.
"It is disgusting they are now looking for a dead man as a scapegoat," she said. "It's very easy to blame someone who can't defend themselves any more. My husband would never be capable of committing such a crime."