Toxicology is One Weapon in a Forensic Investigator's Arsenal

By Kathy Dix

Drug-facilitated sexual assault (DFSA) is one more growing trend to which forensic nurses must be attuned. The most common drug involved in DFSA is a ubiquitous one: alcohol. But other "date-rape" drugs can include gamma hydroxybutyrate (GHB), flunitrazepam (Rohypnol), ketamine (Ketaset or Ketalar) or methylenedioxymethamphetamine (Ecstasy).

Identifying sexual assaults that are drug-assisted is not always easy. "There are few physical signs of this type of drug intoxication," says Graham Jones, chief toxicologist in the Chief Medical Examiner's Office in Edmonton, Alberta, Canada, and secretary of the Society of Forensic Toxicologists (SOFT). "Perhaps the best indication of a drug-facilitated assault is where the degree of intoxication or loss of consciousness, and particularly lack of memory of events, cannot be accounted for by the amount of alcohol ingested."

The victim may not be a good source of information, either, Jones says, because he or she is "embarrassed about the amount of alcohol willingly consumed (and may downplay the amount), or may indeed have a poor memory of events. Also, the amount of alcohol tolerated by someone who drinks frequently will usually be much greater than that of someone who drinks the occasional glass of wine or beer."

Even if the patient does remember whether he or she had one drink or six, the actual amount of alcohol in the drink isn't set in stone.

"In a non-licensed setting (e.g., apartment or home) a drink could easily contain 3 ounces of liquor, depending on the person pouring them," Jones says. "For example, 'a couple' of drinks could mean as much as 6-plus ounces of liquor. In any case of DFSA, obtaining the glass the victim drank from can be extremely important, and in some cases may be the only evidence that the person was drugged."

The original glass may be difficult to come by, so the forensic nurse or investigator must interview the patient regarding what medications he or she is taking, or has taken recently. "It should be borne in mind that many people differentiate 'drugs' from 'medications,'" Jones cautions. "Therefore, asking someone about what 'drugs' they may have taken recently may elicit the response 'none' (although the person may have taken one or more over-the-counter [OTC] meds). It should equally be borne in mind that most 'drugs' detected in DFSA cases are neither GHB nor flunitrazepam, but are other prescription and OTC medications."

If the victim is deceased, the clinical investigator will generally have nothing more to do with the case. "However, it is important to retain incidental materials that might have been brought in with the body (e.g. medications, drinking glasses etc)," Jones notes.

A forensic nurse working as a death investigator for a coroner or medical examiner (ME), however, should carefully document all medications and other containers found at a scene.

"In particular, an increasing number of deaths are being attributed to drug intoxication due to impaired metabolism (rather than abuse or suicidal overdose)," Jones explains. "Such cases can very difficult to determine accurately unless the investigator carefully documents the medications and performs a medication count (i.e., counts the meds present; documents the date dispensed, number dispensed, dose, and therefore is able to determine if there are any missing). Of course, this is not foolproof. People may be sporadically non-compliant, they may share or sell meds, and even transfer meds among containers."

"In most jurisdictions, nursing staff are not allowed to draw samples from a victim without some type of authorization," Jones notes. "In DFSA cases, the most valuable 'exhibit' for toxicology testing is the liquid (or vessel) suspected to have contained the drug. If medically or legally allowable, samples of both blood and urine should be collected (at least 10 ml each) as soon as possible after the DFSA."

Time is of the essence, as some "date rape" drugs are only evident for a short time. "GHB is reputedly only detectable in blood for about 6 hours and in urine for 12 hours," Jones explains. "However, there is a great deal of variability. The capability of the laboratory that performs the analysis has an enormous impact on detectability. For example, neither GHB nor flunitrazepam (e.g. Rohypnol) are detected by most routine toxicology testing. Samples for DFSA should generally only be sent to a forensic laboratory that has methods designed for that type of testing."

Blood and urine are the most common sources for drug testing. But occasionally, hair can be used. "For the purposes of DFSA, hair has very limited value," Jones cautions. "Only a very small number of (toxicologists) perform hair testing for specific drugs of abuse, and an even smaller number perform testing for the types of drugs likely to be encountered in DFSA."

There are two reasons why hair is generally not a good source for drug detection. "First, concentrations of drugs in hair are much lower than in blood or urine, and therefore testing much more difficult. The second problem is that because of the relatively slow rate of growth of hair, little uptake will occur in the hours following the DFSA and therefore any drug present will be close to the root. That means that even if such testing can be performed, the hair has to be plucked, not cut," Jones clarifies.

"There have been one or two papers published recently where a suspected DFSA victim has been asked to come back several weeks after the assault before a hair sample is taken. The hair is then cut into sections and each section analyzed. That way the drugs show up as 'spikes,' corresponding to the estimated date of assault. However, such testing is time-consuming and far from routine. Most testing for DFSA still relies on collection of blood and/or urine as close to the time of the assault as possible."

If a nurse suspects that a patient is (or was) under the influence of a drug or toxin, that is not enough; generally, nurses can only collect biological fluids with a physician's order. And the physician is only allowed to order tests that are required to direct clinical management of a patient. "A nurse who collects specimens just because they think the person may be impaired could be charged with assault in most jurisdictions (unless the person has provided signed consent which specifically authorizes it)," Jones says. "For example, if a nurse sees an injured driver in the emergency room and thinks they may be intoxicated, they absolutely cannot take a blood (or urine) sample, unless a physician has ordered an 'alcohol' test for clinical purposes. That clinical purpose might reasonably be to help determine if a patient's reduced level of consciousness is due to alcohol intoxication or a brain injury."

Unless a forensic nurse is appointed as a coroner, she won't generally have to collect evidence. Occasionally, though, Jones says, "They may be asked by the coroner or ME to collect specimens that were collected from or drawn from an individual while (the patient was still) alive. If somebody goes into the hospital (like to the emergency room) and they survive for some period of time, it can be important to collect the clinical specimens from when they were first admitted, particularly with alcohol." This, Jones explains, is because most people can clear a near-lethal level of alcohol in 18 to 24 hours.

"So if somebody goes into the hospital and they survive for eight hours, they can clear a pretty large amount of alcohol, enough to take them from well above the legal limit to well below the legal limit," he adds. "That's why collection of specimens drawn on admission are so important. With drugs, the same applies; you need to see if you can get a hold of specimens drawn when they were first admitted."

Many forensic nurses may have little interaction with toxicologists. This is not to say that there is a problem between nurses and toxicologists, just that there may be little reason for them to interrelate. "Generally, if toxicologists require information from nursing staff, it is to help determine why a particular test is being ordered, or more commonly, to help interpret drug levels that have been measured," Jones says. "Is the person showing signs of toxicity? How long? How long has the person been on the medication; at what dose? Have other medications been added recently? Most questions in interpretation arise because blood levels may be much higher or lower than expected given the dose. Is the patient compliant? Are the medications controlled by nursing staff?"

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