COEUR D'ALENE, Idaho -- The death sentence is the ultimate punishment for the most heinous crimes.

On Saturday, a North Idaho jury handed Jonathan Renfro that sentence. Renfro was convicted of first degree murder for killing Coeur d'Alene Police Sergeant Greg Moore in 2015.

Renfro will join eight others on death row in the state of Idaho. KREM 2 learned death penalty cases like this are extremely rare and it can be decades before a death row inmate's fate is sealed.

A 2014 study done by Office of Performance Evaluations for the Idaho Legislature said since 1998 the death penalty was sought in just 22 percent of cases where people were charged with first degree murder. Just seven of those cases resulted in an actual death sentence.

Currently, the state of Idaho has eight inmates on death row. The inmate who has spent the longest time on death row is Thomas Creech, who was incarcerated 34 years ago. He was convicted of beating an inmate to death.

According to the Death Penalty Information Center there is only one death row inmate in the federal prison system who was prosecuted in Idaho, convicted child killer Joseph Duncan. Duncan was sentenced to death in 2008. He plead guilty to a 10-count indictment charging him with multiple crimes related to the 2005 kidnapping and murder of a 9-year-old Dylan Groene and the kidnapping of 9-year-old Shasta Groene from their home outside Coeur d'Alene.

Since Idaho enacted a new death penalty law in 1977, just three inmates have been executed. These executions took place in 1994, 2011 and 2012.

It can take decades for a death sentence to actually be carried out. Of the eight people sitting on death row, six of them have been on death row for more than 20 years.

Prosecutors said all appeals must be exhausted before that step is taken. The Idaho Supreme Court is required by law to review every death sentence whether the defendant wants them to or not.

In recent years there has been two notable former Idaho death row inmates, who used the appeal process and were eventually set free.

In the 1984, Charles Fain was convicted and sentence to die for the murder a 9-year-old girl in Nampa, Idaho. DNA evidence exonerated him after 18 years on death row.

Donald Paradis was accused of murdering a couple in his Spokane home and dumping their bodies in Post Falls in the 1980. He was a leader of the biker gang Gyspy Jokers. Paradis was acquitted in one murder and found guilty in the other. Paradis spent 14 years on death row before his sentence was commuted after new evidence was found.