31 Miss. Code. R. 501-6.1
In all Medical Examiner cases, the investigating Medical Examiner shall obtain specimens of blood, urine and/or vitreous humor as the condition of the body permits. If the patient has been treated in a hospital, emergency room, or other health care facility immediately prior to death, such specimens should be taken into custody by the investigating Medical Examiner. With the exception of motor vehicle fatalities (see below), specimens obtained as noted above may be submitted immediately for toxicologic examination or may be retained in refrigerated storage for examination at a later time, at the discretion of the investigating Medical Examiner. In all instances of motor vehicle fatalities, including operators, passengers and pedestrians, specimens shall be submitted to the Mississippi Crime Laboratory for toxicologic examination. If toxicologic examination is deemed necessary, and the condition of the body prohibits recovery of urine, blood or vitreous humor, specimens of brain, lung, kidney, spleen and/or other tissues should be submitted for analysis.
31 Miss. Code. R. 501-6.1