Mark Dean Schwab, 39, is scheduled to die exactly 16 years after he was sentenced in the 1991 kidnapping, rape and murder of 11-year-old Junny Rios-Martinez.

Florida officials say they have resolved problems with the December 2006 execution of Angel Diaz when needles were accidentally pushed through his veins, causing the lethal chemicals to go into his muscles instead, delaying his death for 34 minutes — twice as long as normal. Some experts said that would cause intense pain.

Then-Gov. Jeb Bush stopped all executions after Diaz was killed, but Florida and other states were also held up as they waited for the U.S. Supreme Court to rule the three-drug method of lethal injection used by Kentucky was constitutional. Thirty-four other states, including Florida, use a similar method.

Florida's new procedure requires the warden to make sure the inmate is unconscious following the injection of the first chemical, sodium pentothal. Then the executioner will inject pancuronium bromide to paralyze his muscles and potassium chloride to stop his heart. It also requires people with medical training to be involved in the process.

Schwab and his attorneys aren't so sure the problems are fixed. An analysis done for Schwab's lawyers showed that nine of the 30 mock executions performed by Florida's Department of Corrections between September 2007 and May were failures, said one of his state-paid attorneys, Mark Gruber.

The corrections department said its mock exercises have included preparation for potential problems such as a combative inmate, the incapacity of an execution team member, power failure and finding a vein.