Oklahoma prison officials unveiled a revamped execution chamber Thursday, following the controversy surrounding a botched execution in April that drew widespread condemnation.

The reconstruction of the death chamber cost $71,000, including $34,000 on new medical equipment, $12,500 for a surgical table and $6,000 for an ultrasound machine to help locate veins. The execution chamber and adjoining witness rooms have also been remodeled to give executioners and witnesses more room, according to a report from the Associated Press. Three men are scheduled to be executed in the facility by the end of the year.

In April, convicted murderer Clayton Lockett died of a massive heart attack minutes after a doctor halted his execution. He took almost 40 minutes to die after the procedure started, attracting widespread criticism that his execution amounted to cruel and unusual punishment.

The revamped chamber has cameras, video screens and a heartbeat monitor, which enables executioners to track the progress of executions, and a new ultrasound machine that will allow them to locate a condemned prisoner's veins, according to a BBC report

In addition to the improvements, the state has also put in place new execution protocols, including increasing the dosage of a controversial sedative and allowing the corrections department director to choose from four lethal injection options, according to a Reuters report

U.S. states that practice the death penalty by lethal injection have faced a raft of problems in recent months, following a European-led boycott aimed at denying corrections departments the drugs they require to carry out the procedure. 

States including Georgia, Missouri, Arkansas and Texas -- the U.S. state that performs the largest number of executions each year -- have struggled to find workable alternatives to the previously available drug formulas. Charles Warner, who was originally scheduled to be executed shortly after Lockett, is the next inmate scheduled to be executed in Oklahoma, with his execution scheduled for Nov. 13.