New Delhi: With a controversial lethal injection of drug, the US state of Tennesse executed a pedophile convict.

The man was accused of raping and then killing child and the country’s apex court declined his bid for a stay.

The last words of the convict, Billy Irick, were: “I just want to say I’m really sorry. And that..that’s it.” He said this to prison officials.

Irick became the first inmate to be executed in Tennessee since 2009.

The drug used for execution had raised concerns about the convict potentially feeling sensations equivalent to being burnt alive. In an appeal to the Supreme Court, Irick's lawyers challenged Tennessee's lethal injection protocol, which included the use of the sedative midazolam.

The Supreme Court had denied a stay of execution , rejecting all the concerns.

This was met by dissent from Justice Sonia Sotomayor, who questioned whether Irick’s execution would be too painful and whether allowing it to proceed required accepting “barbarism”.

As reported by AFP, Sotomayor wrote that the three-drug cocktail that would be injected in Irick’s vein would make him experience sensations of drowning, suffocating, and being burned alive from the inside out, medical experts explained.

Other states have also used the drug for executions with mixed results.

Medical experts too had warned that the drug may not be strong enough to keep a prisoner unconscious once he starts to feel pain. A paralytic used as the second drug in Tennessee's lethal injection would prevent Irick from alerting officials that he can feel pain, in case he is awakens.

Use of midazolam for execution has been a matter of debate in the state.

As per reports, the 59-year-old was convicted in 1986 of raping and killing seven-year-old Paula Dyer. His lawyers have argued Irick has a history of severe mental illness.