Some murderers do get parole after 25 to 30 years in prison.
That is if the person was convicted of murder and sentenced to life with parole or they were sentenced to 25 years to life with parole.
If the murderer was sentenced to life without parole then the murderer will remain in prison until they die and the only way the person is leaving prison is in a body bag.
So most murderers remain in prison for the rest of their lives and die behind bars.
However some murderers are sentenced to death and in that case the death row inmate will remain on death row for around 10 to 15 years before they are actually executed.
The death row inmate will remain in an isolated prison cell for 23 hours per day with 1 hour outside in a rec cage for exercise.
Then they go back to the death row cell and spend the rest of their time there with nothing but a toilet, sometimes a shower and the death row inmates meals are brought to them through a slot in the door.