Arkansas wrapped up an aggressive execution schedule Thursday, putting to death its fourth inmate in eight days.

Kenneth Williams, 38, received a lethal injection Thursday night at the Cummins Unit prison at Varner for the death of a former deputy warden killed after Williams escaped from prison in 1999. At the time of his escape in a 500—gallon barrel of hog slop, Williams was less than three weeks into a life term for the death of a college cheerleader.

Arkansas had scheduled eight executions over an 11day period before one of its lethal injection drugs expires at the end of April, the most in such a compressed period since the U.S. Supreme Court reinstated the death penalty in 1976. Among the four lethal injections was Monday’s first double execution in the United States since 2000. Courts issued stays for four other inmates.

State officials have declared the string of executions a success, using terms like “closure” for the victims’ families. The inmates have died within 20 minutes of their executions beginning, a contrast from midazolam-related executions in other states that took anywhere from 43 minutes to two hours. The inmates’ lawyers have said there are still flaws and that there is no certainty that the inmates aren’t suffering while they die.

Arkansas scheduled the executions for the final two weeks of April because its supply of midazolam, normally a surgical sedative, expires on Sunday. The Arkansas Department of Correction has said it has no new source for the drug though it has made similar remarks previously yet still found a new stash.

Williams was sentenced to death for killing Cecil Boren after escaping from the Cummins Unit prison in a barrel holding a mishmash of kitchen scraps. He left the prison where the execution chamber is located in another part of the facility less than three weeks into a life prison term for killing University of Arkansas at Pine Bluff cheerleader Dominique Hurd in 1998. At the conclusion of that trial, he had taunted the young woman’s family by turning to them after the sentence was announced and saying “You thought I was going to die, didn’t you?”

After jumping from the barrel, he sneaked along a tree line until reaching Boren’s house. He killed Boren, stole guns and Boren’s truck and then drove away to Missouri. There, he crashed into a water-delivery truck, killing the driver. While in prison, he confessed to killing another person in 1998.

At the time of Boren’s death, investigators said it did not appear Boren was targeted because of his former employment by the Arkansas Department of Correction.