What is the relevant age for a crime? When it is committed, when one is charged of it, or when one is sentenced for it?

Question

Bob committed a crime when he was young. After successfully getting away, many years later, it comes out (with good evidence) that he committed the crime, and so he is charged for it. Lastly, after many years in court (due to any number of complicating factors), Bob is finally successfully convicted.

My question is, when sentencing Bob, which age is the most relevant? The age when he committed the crime, the age when he was charged, or the age when he was convicted in court?

Just two examples:

1. Bob committed murder at age 12, was caught and convicted at age 25
2. Bob committed murder at age 14, was charged at age 16, and only successfully convicted at age 19

Feel free to swap out the crime/ages with what you think is most relevant.

Edit: Of particular note for consideration: isn't the fact that Bob, as an adult, hides a murder, worthy of being charged for any crime whatsoever?

Answer 1

england-and-wales

It's the date, and therefore Bob's age, when the offence was committed

The basic position when an offender is sentenced is that it should be according to the law at the time the offence was committed, not the law at the time when they are sentenced. This has been reinforced by Article 7 of the European Convention of Human Rights.

It is a general legal principle that the law should not be applied retrospectively – so that people are able to know the penalty for an offence.

Source

Answer 2

In the U.S. Bob is of age to be criminally responsiblity is set by Indivdual States. This Age denotes the youngest possible age that a person can be held criminally liable for a crime. Federally, this age is 11 years old. Massachusetts has the oldest criminal liability age, at 12 years of age, so had he been one year younger and committed the crime in Massachusetts, Bob would never have been charged, even if he was 25 at the time the case was solved.

With that said, in both cases, Bob being charged as a juvenile vs. charged as an adult is case specific and tends to reflect upon factors of Bob's and Bob's mental motive for committing the crime, though typically in murder cases, most children over 10 years old are charged as adults. At either rate, as Bob is a minor at the time of the crime, he would be ineligible for the death penalty regardless of the age he was not a legal adult at the time and the supreme court has determined that subjecting minor offenders to death penalty is cruel and unusual punishment.

For any other case other than murder or rape, scenario one would not result in Bob being charged and convicted as Statute of Limitations would have existed for the crimes. Typically, unless stated by law, statute of limitations is typically 5 years following the date of the last criminal act. Afterwards, the case would be tossed. Murder and Rape have no statute of limitations, and thus can be prosecuted any number of years following the criminal action (Rape has only recently had statute of limitations removed, so there are cases that are still not possible to prosecute because they happened prior to the change in the law, however, it's highly unlikely that a teenager would have been able to take advantage of this change.