Maryland Law on Sexual Assault. From what I have read there is no Statute of Limitations.

Sexual Offense
First Degree – Usually this crime or attempt of this crime is subject to life imprisonment. However, if a person was previously convicted of first-degree rape or sexual offense, commits the rape on a kidnapped child under 16, or the defendant is over 18 and the victim was under 13, then life imprisonment without the possibility of parole is the maximum sentence.
Note: The same 25-year mandatory minimum prison sentence applies here if the defendant was over 18 and the victim was a child under 13. None of the 25 years can be suspended by the court, nor is the person eligible for parole.
Second Degree – Usually, the punishment is a maximum of 20 years in prison, including for attempt. However, if a person 18 years or older sexual assaults a child under 13 the minimum prison term is 15 years and maximum is life in prison.
Third Degree – A felony with a sentence not more than 10 years in prison
Fourth Degree – Typically, this crime is a misdemeanor punished by not more than one-year imprisonment and a fine not more than $1,000. However, if a person previously committed a sex crime, the punishment is increased to 3 years in prison and a fine up to $1,000.