Amnesty International has released its annual death penalty report, which shows the number of countries that use capital punishment is declining. But the report estimates that China executed several thousand people in 2009.
Arthur Judah Angel was sentenced to death in Nigeria in 1986 for a crime he says he didn't commit.
"Being on death row was like being in hell. You understand? In fact, it's very horrible. I don't have enough language – in English or my own - to explain it," said Angel.
He was 21-years-old when he was arrested and spent the next 16 years in prison. Every night he was there, he says, he had nightmares.
He says inside the cell he wasn't even able to stretch his legs.
"The size of the cell measured exactly seven feet by eight. We have the toilet bucket occupying about two feet square in there. And we sleep sometimes 13 of us to a room," he adds.
He says he thought each day might be his last.
"I witnessed the execution of nothing less than 450 - I can still remember their names. From Monday to Friday from 8 a.m. to noon, it would be anybody, "Angel said.
Today over 800 people are on death row in Nigeria, but in 2009 no one was executed.
Across Sub-Saharan Africa only two countries carried out executions, Sudan and Botswana.
In Kenya, more than 4,000 prisoners had their death sentences commuted to imprisonment.
And, says Philip Luther from Amnesty International, two sub-Saharan countries abolished the penalty.
"Burundi and Togo abolished the death penalty for all crimes in 2009 and that was certainly a further sign of the world continuing its move towards abolishment," said Luther.
But he says in some countries the number of executions remains high. Amnesty estimates several thousand people were executed in China in 2009, but Luther says an exact figure is impossible to gauge.
"There is sort of a shroud of secrecy that hangs over the death penalty in China and we are challenging China in this report to lift that shroud of secrecy," adds Luther. "China, in fact, has said that it has decreased the use of the death penalty in the country, but frankly it needs to make those statistics public to show this is really the case."
Beijing says details of its executions are a state secret. But it says the number of executions has gone down since 2007, after it became mandatory for death sentences to be reviewed by a higher court.
Outside of China, Amnesty says 714 people were executed in 18 countries in 2009. The countries that carried out the highest number of executions were Iran, Iraq, Saudi Arabia and the United States.
Amnesty warned that some countries are using capital punishment to send political messages, silence opponents or promote political agendas – this is especially the case, it says, in China, Sudan, and Iran.
"What we do see and this is a reflection of some of the wider trends is that if you take Iran, the use of the death penalty to send political messages or to silence opponents was very clear I think," said Luther. "That pattern was particularly acute in the period, the two months following the presidential election in June 2009."
In Iran 388 people were executed in 2009. Luther says 112 of those took place in the eight weeks following the presidential election.
Amnesty says for the first time since it began keeping records there were no executions in Europe.