For full toxicological analysis, it is recommended that the submitting agency provide the following:
§ (Blood) A total of at least 14mL of blood collected in two test tubes with sodium fluoride and potassium oxalate preservatives, i.e., gray-topped tubes (best for DWI)
§ (Urine) 50mL of urine collected in a urine specimen bottle or urine specimen cup (best for Drug Facilitated Sexual Assault)
Each specimen tube, bottle or cup must be labeled with the following:
§ Name of the individual from whom the specimen was collected
§ Date and time of collection
§ Initials of the individual who collected the specimen
Each specimen tube, bottle or cup should be stored inside a specimen container, such as a cardboard box, envelope or plastic bag. It is acceptable to include multiple specimen tubes, bottles or cups in one specimen container if they all pertain to the same case. The specimen container should be sealed with evidence tape and must be labeled with the following:
§ Initials of the individual submitting the specimen container – initials must be written across both the tape and the container
§ Name of the submitting law enforcement agency
§ Case number
To maintain the integrity of the specimen, a chain of custody should be initiated upon collection and the specimen should be refrigerated as soon as possible.
Regular Business Hours: Monday through Friday, 8 a.m. – 5 p.m.
Submit specimens to the Harris County Institute of Forensic Sciences Evidence Reception located at 1885 Old Spanish Trail, Houston, Texas.
Afterhours, Weekends and on Harris County Holidays
Submit specimens at the afterhours evidence submission location, which can be accessed at the rear of the Institute’s building located at 1885 Old Spanish Trail, Houston, Texas.
A submission form must be completed at the time of submission and must accompany the submission. Do not attach the form to the specimen container.
Click here to download the submission form or request a form from the Institute’s Evidence Receiving staff during regular business hours.
Result Reporting for DWI Testing
In suspected Driving While Intoxicated (DWI) cases, blood specimens first undergo alcohol testing. If the blood alcohol level is greater than or equal to 0.17 g/100mL, no further testing is performed unless specifically requested. If the blood alcohol level is less than 0.17 g/100mL, drug screening and confirmation is performed.
When the recommended volume of blood or urine is not received, some testing may not be possible. For example, when the specimen sample volume is not sufficient for both drug screening and confirmation tests, positive screening results will be reported as “Presumptive positive.” In these instances, a forensic toxicologist may contact the submitting law enforcement agency to discuss the need for drug confirmation tests. When sample volume is not sufficient for any type of testing, results will be reported as “Quantity not sufficient.”