M.R.M. 10 is a multi-component fluorescent dye-stain solution. It's designed to enhance the visualization of latent fingerprints that have been previously developed with cyanoacrylate ester ("superglue") fuming. M.R.M. 10 is particularly useful on non-porous surfaces.
Equipment
- Fume Hood: For handling the chemicals involved in mixing and using M.R.M. 10.
- Gloves: Nitrile or similar chemical-resistant gloves
- Eye Protection: Safety glasses or goggles are a must.
- Spray Bottle, Beaker, or Tray: Choose a method for application – spraying, dipping, or using a squirt bottle.
- Forensic Light Source (ALS): Excitation wavelength between 430 nm and 530 nm.
- Orange Filter: For the camera lens or viewing goggles
Ingredients for 1-Liter M.R.M. 10 Solution
- Rhodamine 6G: 1 gram
- Basic Yellow 40: 2 grams
- M.B.D. (7-(p-methoxybenzylamino)-4-nitrobenz-2-oxa-1,3-diazole): 1 gram
- Methanol: 2 liters
- Acetone: 1 liter
Mixing Procedure
- Safety First: Work in a well-ventilated fume hood, wearing gloves and eye protection.
- Stock Solutions: Make three separate stock solutions:
- Stock A: Dissolve 1 gram Rhodamine 6G in 1 liter methanol.
- Stock B: Dissolve 2 grams Basic Yellow 40 in 1 liter methanol.
- Stock C: Dissolve 1 gram M.B.D. in 1 liter acetone.
- M.R.M. 10 Working Solution: Using a clean container, combine the stock solutions with gentle mixing until well blended.
Latent Print Development with M.R.M. 10
- Cyanoacrylate Fuming: First, develop any latent prints using the cyanoacrylate fuming process.
- Apply M.R.M. 10: Apply the M.R.M. 10 solution via your chosen method (spraying, dipping, etc.). Ensure complete coverage of the areas where cyanoacrylate was deposited.
- Rinse: Optionally, you may rinse the item gently with distilled water to reduce background staining.
- Examination: In a dark environment, examine the treated surface with your forensic light source. Utilize the orange filter for optimal visualization.
- Photography: Always document the enhanced fingerprints with photography using the orange filter on your camera.
Storage and Shelf Life
- Light-Sensitive: Stock solutions and the working solution of M.R.M. 10 are light-sensitive. Store them in amber bottles to reduce degradation.
- Cool and Dry: Choose a storage location that's cool, dry, and out of direct sunlight.
- Shelf Life: The working solution of M.R.M. 10 generally has a shelf life of around 6 months when stored properly.
Important Considerations
- Always work within a controlled environment like a fume hood. Some of the ingredients can be hazardous with exposure.
- M.R.M. 10 is a multi-step reagent often used in a sequence of latent print development techniques.
- Background fluorescence of certain substrates can sometimes create complications for examiners. Be mindful.