I found this on the Louisiana Criminal Procedure website about limitations in time and prosecuting cases:

Art. 572. Limitation of prosecution of noncapital offenses

A. Except as provided in Articles 571 and 571.1, no person shall be prosecuted, tried, or punished for an offense not punishable by death or life imprisonment, unless the prosecution is instituted within the following periods of time after the offense has been committed:

(1) Six years, for a felony necessarily punishable by imprisonment at hard labor.

(2) Four years, for a felony not necessarily punishable by imprisonment at hard labor.

(3) Two years, for a misdemeanor punishable by a fine, or imprisonment, or both.

(4) Six months, for a misdemeanor punishable only by a fine or forfeiture.

B.(1) Notwithstanding the provisions of Article 571.1 and Paragraph A of this Article, prosecutions for any sex offense may be commenced beyond the time limitations set forth in this Title if the identity of the offender is established after the expiration of such time limitation through the use of a DNA profile.

(2) A prosecution under the exception provided by this Paragraph shall be commenced within three years from the date on which the identity of the suspect is established by DNA testing.

(3) For purposes of this Article, “DNA” means deoxyribonucleic acid, which is located in cells and provides an individual’s personal genetic blue print and which encodes genetic information that is the basis of human heredity and forensic identification.

(4) This Paragraph shall have retroactive application to crimes committed prior to June 20, 2003.

C. Upon expiration of the time period in which a prosecution may be instituted, any bail bond applicable to that prosecution which bond has not been forfeited shall also expire, and all obligations of that bail undertaking shall be extinguished as a matter of law.

Amended by Acts 1984, No. 926, §1; Acts 2001, No. 207, §1; Acts 2003, No. 487, §2, eff. June 20, 2003; Acts 2003, No. 809, §1, eff. July 1, 2003; Acts 2006, No. 123, §1, eff. June 2, 2006.

NOTE: See Acts 2003, No. 487, §5, relative to application.

You can find out more by going to:
http://www.legis.state.la.us/lss/lss.asp?doc=112622