BOISE, Feb 29 — Idaho botched its attempt to execute a 73-year-old prisoner yesterday, abandoning the lethal injection and sending the convicted murderer back to his cell after repeatedly failing to find a suitable vein, officials said.

Executioners tried at least eight times to insert an intravenous line in Thomas Eugene Creech, a convicted serial killer who has been in prison since 1974, Josh Tewalt, director of the Idaho Department of Correction, said at a press conference.

For nearly an hour, they tried inserting the line in "multiple limbs and appendages” after strapping Creech to a gurney, Tewalt said.

"It was a vein quality issue,” he said at the Idaho Maximum Security Institution, a few hours after the US Supreme Court had rejected Creech’s petition for a stay of execution.

Among other arguments, Creech’s lawyers said that Idaho’s secrecy around its lethal-injection protocol made it impossible for him to weigh whether the state was violating a constitutional ban on cruel and unusual punishment.

Multiple US states that carry out executions have faced similar problems in finding veins in aging or overweight prisoners, or struggled to find the required drugs. This has prompted state lawmakers to revive older methods, such as firing squads, or develop new ones, such as Alabama’s pioneering use last month of nitrogen to asphyxiate a prisoner.

Idaho planned to let Creech’s death warrant expire, and Tewalt said it was not clear whether the state would pursue a new warrant at a later date.

Creech’s lawyers said in a statement they were "angered but not surprised” by the botched execution attempt.

"This is what happens when unknown individuals with unknown training are assigned to carry out an execution,” the Federal Defender Service of Idaho said. "This is precisely the kind of mishap we warned the State and the Courts could happen when attempting to execute one of the country’s oldest death-row inmates in circumstances completely shielded in secrecy despite a well-known history of getting drugs from shady sources.”

Creech was convicted of murdering five people in the 1970s before being sent to prison, and then sentenced to death by a judge after murdering another prisoner, David Jensen, in the maximum-security facility where he was held. — Reuters