Do not allow civilians or family members access to the scene. This may sound obvious, but in the Jon Benet Ramsey case, the family and several friends were allowed to stay in the home for hours. In an attempt to alleviate their restlessness, the lone officer at the scene allowed them to search the house.
The girl's body was found by her father in the basement, which had not been previously searched. In this case potential suspects were allowed to roam freely about the scene. Even if they were not the perpetrators of the crime, they surely contaminated and destroyed evidence.
Forensic evidence: What to look for
Almost anything imaginable can be evidence at the scene of a sexual assault. If something looks out of place, collect it even if its connection to the crime or identification is unknown. The following are some of the more common types of evidence.
Body fluids such as semen, saliva, urine, sweat or mucus contain DNA. As well, these types of biological samples can be used for toxicological and serological testing. These tests can reveal the use of particular drugs (toxicology) or things such as blood type (serology). Common sources of this type of evidence are:
- Sheets and other bedding, as well as fabric off furniture and vehicle upholstery
- Window panes and sills outside the residence
There have been cases where perpetrators watched their victims from outside and left body fluids on windows, etc. Cigarettes may be found in locations where the perpetrator hid outside. These are also a source of DNA. Both saliva and skin cells can be found on cigarettes.
- Garbage cans — may contain tissues and used condoms
- Anything that may have been used as a weapon may have skin cells or blood on it
- Broken windows and other glass fragments may have blood from the perpetrator on it.
Perpetrators can cut themselves while breaking windows or other glass items.
- Partially eaten food or gum
- Swabs from the victim's mouth, anus or vagina
- Clothing from the victim or suspect
Standard toxicological screening of the victim's or suspect's blood, urine or saliva can reveal whether drugs (prescription or street) or alcohol were present. The lab can be asked to test for the presence of chemicals associated with benzodiazepines such as Rohypnol.
Date rape drugs. Rohypnol is one of the more prevalent drugs used in the United States as a date rape drug. Originally it was produced as an anti-depressant and a sleeping pill by Hoffman La Roche Pharmaceuticals for use in Europe but has never been approved for use in the states. It was introduced to the country via Mexico in the 1990s.
The drug Rohypnol was originally produced as a white tablet embossed with the word "Roche." It eventually became known as a "date rape" drug, which was commonly administered to unsuspecting victims by mixing it into an alcoholic drink. The manufacturer changed the color, and it is now a green pill implanted with a blue dye, which is easily detected if mixed into a drink. In the United States, the older white pills are most common.
Rohypnol can be smoked, injected or ingested. The effects usually last between 8 and 12 hours. The important thing in terms of forensic evidence is that Rohypnol has a half-life of 9 to 25 hours. After this period it is not detectable in blood samples. It will be detectable in urine samples within 2 to 5 days if the lab is directed to look for significantly smaller concentrations than is the standard.
The first case of the drug being used as a date rape drug occurred in Florida in 1992. To date, several thousand cases have been reported around the country. This figure is probably just the tip of the iceberg due to the low rate of reporting (less than 5 percent). This drug is usually used in combination with alcohol which can produce memory loss. Victims may feel they don't remember enough about the assault to report it.
Rohypnol is known by many street names. Some of the more common names are "roofies," "ruffies," "R-1 and R-2" (indicated in the dosage), "RTF" and "Mexican valium," but new names appear regularly.
GHB. Gamma-hydroxybutyrate is most commonly known as Ecstasy. It is actually a chemical produced naturally in the cells of all mammals. Originally produced in the 1920s, it has been used as an anesthetic and later by athletes as a steroid. It was also available as a pain killer for horses and cattle up until the 1980s, readily available at livestock supply stores.