Andrew Lavern Smith was put to death by lethal injection in South Carolina for murdering an elderly couple 15 years ago.

He was convicted of killing Christy and Corrie Johnson after they refused to let him borrow their car. Mr and Mrs Johnson were stabbed a total of 44 times in a frenzied attack.

As the curtain was drawn on the death chamber at Broad River Correctional Institute, Smith was seen singing Amazing Grace.

Outside the prison a small group of death penalty opponents sat on the road refusing to move.

The South Carolina Coalition Against the Death Penalty lit candles for the 500 prisoners executed since 1976.

State Attorney General Charlie Condon said: "I prefer to think of this as an occasion to remember the victims - the men, women and children slaughtered by 500 cold-blooded killers."

Return to death row

A majority of Americans favour capital punishment and 38 states have the death penalty.

But human rights groups say prisoners are more likely to be executed if they are black or poor.

They also point out that since 1976, more than 70 of those executed have later been found to be innocent.

In 1972, the Supreme Court ruled execution was unconstitutionally "cruel and unusual" because states used it in arbitrary and capricious ways.

The high court ended its nationwide ban on capital punishment in 1976 and executions resumed the following year.

Initially, the pace of executions was slow. In 1977 only Gary Gilmore was executed by firing squad in Utah.

Only 11 executions took place in the first seven years after capital punishment was restored to the statute book.

In 1997 there were 74 executions last year and so far this year, there have been 68, including Smith.

About 3,500 US prisoners are currently on death row.