Suspected serial killer first to be executed by Texas' new lethal injection supply

Death of convicted killer comes amid controversy over where prison officials sourced the pentobarbital, a drug widely used in American state executions

A suspected serial killer convicted of stabbing a 13-year-old girl to death has been executed in Texas amid controversy over where the state sourced the lethal injection.

Tommy Lynn Sells, 49, was the first inmate to be put to death using a dose of newly replenished pentobarbital stocks obtained by Texas prison officials.

American states have began to struggle to obtain the drugs used in executions after a number of predominantly European firms began refusing to sell them for the purpose.

In January of this year Ohio used an untested cocktail of drugs to execute a man which resulted in him taking 25 minutes to die, during which time he snorted and gulped for air.

In the same month an Oklahoma inmate’s final words were “I feel my whole body burning,” spoke 20 seconds after receiving the injection.

Sells was the 15th person executed in the United States this year and the fifth in Texas, which executes more people than any other state in the country.

Ohio's 'experimental' execution

Sells' lawyers argued they needed to know the name of the pharmacy now providing the state with pentobarbital used during executions in order to verify the drug's quality and protect Sells from unconstitutional pain and suffering.

But the Supreme Court sided with Texas prison officials, who argued that information about the drug supplier must be kept secret to protect the pharmacy from threats of violence.

Pentobarbital has been used in a large number of executions previously and the appeals court said the case might have been different if the state were using a drug never before used or unheard of, whose effectiveness was completely unknown.

Sells declined to give a statement before death. As the drug began flowing into his arms inside the death chamber in Huntsville, he took a few breaths, his eyes closed and he began to snore. After less than a minute, he stopped moving. He was pronounced dead at 13 minutes after being given the injection.

A jury convicted him of capital murder in 2000 for the stabbing death of Kaylene Harris and slashing the throat of her 10-year-old friend, Krystal Surles, who survived and helped police find Sells.

The girls were attacked on New Year's Eve 1999 as they slept in Harris' home in Del Rio, about 150 miles west of San Antonio, Texas.

Court records show Sells claimed to have committed as many as 70 killings across the US.

In 2003, Sells was indicted but never tried for the slaying of 13-year-old Stephanie Mahaney in Missouri.

He also pleaded guilty to murder in the 1999 death of nine-year-old Mary Bea Perez, who was strangled during an outdoor festival in Texas. Prosecutors waived the death penalty in exchange for the plea.

Additional reporting from agencies