Executed Brazilian prisoner Rodrigo Gularte was allegedly mentally ill and unaware of his impending death this week in Indonesia.

Gularte was one of several convicted drug traffickers killed by firing squad on Wednesday, and was reportedly suffering from paranoid schizophrenia.

The 42-year-old was arrested in Indonesia in 2004 when he tried to enter the country with over 13 pounds of cocaine in his surfing gear. His family, attorney, and the Brazilian government asked for mercy because of Gularte's mental state, but received none. 

In his final days, Gularte's attorney, Ricky Gunawan, tried to communicate the gravity of the situation, but says he could not get through to his client. 

"He had a delusional mind," Gunawab told AFP. "When we said your death sentence will be implemented, he said, 'What death sentence? I will not be sentenced to death.'

"I'm not sure whether he really 100 per cent understood he would be executed."

Gularte's priest, Father Charlie Burrows, also tried to explain his impending execution to him, but to no avail. 

"I thought he'd got the message he was to be executed but.... when the chains started to go on, he said to me, 'Oh Father .. am I being executed?'" Burrows told the Australian Broadcasting Corporation.

"He didn't get angry, he was annoyed," he recounted.

"The big thing was, 'Oh, why is this happening, this is not right, I made a small mistake and why can't they just leave me in jail on the island and I won't give anybody any trouble'.

"I'd thought I'd explained to him what was going to happen. Obviously it didn't get through."

World leaders protested the executions of Gularte, as well as an Indonesian, four Nigerians, and two Australians on Wednesday, calling their sentences unnecessarily cruel. The two Australians, Andrew Chan and Myuran Sukumaran, were members of the Bali Nine drug smuggling ring and had reportedly been reformed in prison. 

Chan became a pastor and media reports stated that the convicts were singing Christian songs as they were led out for their execution by firing squad in the early hours of Wednesday. 

Si Yi Chen, Michael Czugaj, Tan Duc Thanh Nguyen, Matthew Norman, Scott Rush, and Martin Stephens were sentenced to life in prison, while Renae Lawrence received a 20-year sentence.