COLUMBUS, Ohio — A condemned Cleveland killer moved one step closer to execution Tuesday despite a rare plea for mercy from the prosecutor overseeing his case and support from nearly half of a board that previously voted unanimously against him.

The Ohio Parole Board voted 6-4 to turn down a request for clemency for death row inmate Billy Slagle, sentenced to die for stabbing a neighbor 17 times almost three decades ago.

The entire board ruled against clemency two years ago for Slagle, but that was before the election of new Cuyahoga County prosecutor Tim McGinty and a change in his office's approach to capital punishment.

McGinty, who is applying new criteria to both old and new death penalty cases, has said he doesn't believe his office could obtain a death sentence for Slagle today. McGinty is pushing for life without parole, arguing that without that option in 1987, jurors trying to ensure that Slagle would never go free chose the only option before them: a death sentence.

Slagle was convicted in the death that year of Mari Anne Pope, who was killed while two young children she was watching were in the house.

"The egregious nature of Slagle's crime and circumstances surrounding it outweigh the mitigation present here," the parole board wrote in Tuesday's ruling, which called the slaying "unprovoked, merciless, and completely senseless."

McGinty said he respected the board's decision.

"We will continue to make our position known to Gov. John Kasich as he weighs one of the most difficult decisions that any governor must make," the prosecutor said in a statement.

Attorneys for Slagle, 44, have long argued his sentence should be commuted to life without parole, citing his age — at 18, he was the minimum age for execution in Ohio when the crime happened — and a long history of drug and alcohol abuse.

"Billy was exposed to alcohol from the womb to the crime," Joe Wilhelm, a federal public defender, said at a hearing this month.

Wilhelm said Tuesday he was encouraged that four members voted in favor of clemency.

"We have a very strong case and we're hopeful that the governor will do the right thing and commute Billy Slagle's sentence," Wilhelm said.

The parole board members who supported clemency cited McGinty's change of position, with one noting that Slagle's "age and immaturity at the time of offense significantly mitigate his sentence."

In 1996, Ohio law changed to allow jurors to choose between execution and life without parole. In 2005, lawmakers added a provision allowing prosecutors to pursue life without parole in non-death penalty cases.

"Slagle's case is a close call," Cuyahoga County assistant prosecutor Matthew Meyer told the parole board at the hearing. "We can't in confidence tell you that had it happened today, this would be a death case."

Meyer said the recommendation for mercy was not meant to diminish the heinous facts of Pope's death.

Kasich, who has the final say, is not commenting. Slagle's execution is scheduled for Aug. 7.

It's unclear whether a sitting Ohio prosecutor has ever asked that a death row inmate under his office have the sentence commuted.

Cuyahoga County has long had a reputation for heavy use of capital punishment indictments with relatively low numbers of death sentences. McGinty had promised to reduce the number of death penalty charges when he ran for the office.