Dozens of cyclists have contacted officials asking why no drivers have been charged - or cleared - after three crashes killed three bicyclists in Boise since May 19.

The message from police and prosecutors: Be patient. If evidence shows that a crime was committed, the drivers will be charged.

"I tell them we share your interest in keeping the roads safe," Ada County Deputy Prosecutor Roger Bourne said. "We are interested in public safety. We are interested in due process."

Right now, in all three cases, officials are waiting for blood and urine tests to determine if the drivers - or victims - were drunk or under the influence of drugs at the time of the crashes.

Idaho code says the difference between misdemeanor and felony vehicular manslaughter is the presence of "gross negligence." It is also the difference between up to a year in jail and up to 10 years in prison - or even 15, if the driver was under the influence of drugs or alcohol.

"These cases can be incredibly complex - does the evidence show gross negligence?" Bourne said.

"You want to have good science, and good science takes time," said S.C. Williamson, a forensic scientist who oversees the toxicology unit of Idaho State Police Forensic lab in Pocatello. The lab does blood toxicology tests for Boise police.

"Before we decide (whether to charge), we want to be able to prove the case beyond reasonable doubt," Bourne said.

"Making a charging decision in the heat of the moment is not going to help anyone in the long run."

A court records search of recent vehicular manslaughter cases in the Treasure Valley over the past five years - whether they involve cyclists, pedestrians, or other drivers - shows it has taken as long as as six months or more for charges to be filed.

The making of every case breaks down into three steps, and each can take weeks or longer.

1. RECONSTRUCTION: LASERS AND INTERVIEWS

Any time a traffic accident poses the possibility of serious injury or death in Boise, the Police Department's crash unit responds.

That unit, composed of three Boise police officers and a sergeant who specializes in accident reconstruction, uses advanced computer and field equipment to diagram a crash scene.

Special laser equipment is used to map the intersection or road where the crash occurred. It measures tire skid marks and where the cars end up at the conclusion of the accident. The unit has a device to measure the friction of the road, which helps calculate the speed of the vehicles involved.

Officers use all that information to figure out what happened.

Sgt. Dave Cavanaugh, who runs the Boise police crash investigation unit, says it generally takes about three to five days to complete an accident report.

While that unit is doing the scientific analysis, detectives interview witnesses and collect physical evidence at the scene. They get the blood and urine samples.

That process can take "from about two days to two weeks," Boise police Sgt. Mark Barnett said. "Our interviews are usually wrapped up in a week or so."

The detectives also work closely with the Ada County coroner's office, which does an autopsy on the victims and sends the blood and urine samples to the lab.

2. TOXICOLOGY: IT'S MORE THAN YOU SEE ON TV

Boise police officials say it usually takes at least four to six weeks or longer to get blood and urine test results.

If a blood sample needs to be checked for alcohol, it is sent to the ISP forensic lab in Coeur d'Alene. That lab averaged a turnaround time of about 14 days in around 810 cases from January to May, said Matthew Gammette, the laboratory improvement manager of Idaho State Police Forensic Services.

Blood toxicology takes even longer. Only after the blood alcohol content tests are done are the samples sent to the ISP forensic lab in Pocatello.

Williamson, who oversees the toxicology unit, said there are several factors people may not be aware of:

• ISP does blood alcohol and toxicology testing for all law enforcement agencies in Idaho.

• The time it takes to run what could be multiple tests on the same blood and urine samples for different drugs, especially if pharmaceutical drugs are involved.

• The time spent on quality assurance, peer and administrative review, and testifying in court cases.

Forensic scientists will try to expedite blood sample processing from serious criminal cases like vehicular manslaughter, Williamson said.

Crime lab analysts must meet rigorous best practices standards for the actual tests, data analysis and equipment maintenance. In essence, the lab work must meet court and accreditation standards for evidence processing.

On a blood test for marijuana, for instance, if the initial tests shows some evidence of marijuana use, another test has to be done to identify specific marijuana levels. Since tests are done in batches, that itself can take several days.

"First there is preliminary data, then you have to prove it," Williamson said.

"If tests hit for cocaine or meth, there are different extraction procedures for each one. Each component of a test can take days."

Williamson pointed out that in the popular television show "NCIS," there is one character that runs a crime lab. In real life, that lab would have dozens of scientists working in different areas of expertise.

"None of us like the time delays, but it is necessary to have all the evidence," Boise police Sgt. Mark Barnett said. "It takes time."

3. PROSECUTION: MAKING THE CORRECT CALL

Once the toxicology results are in, it's up to the prosecutor's office to decide whether charges should be filed.

Bourne, the deputy prosecutor in Ada County, said this step can be the most time-consuming of all, as prosecutors try to figure out the most appropriate charges - if there is evidence of "gross negligence."

Prosecutors may find they need to do additional witness interviews. Sometimes they have to bring in expert witnesses, like engineers, to go over crash data.

If people are not charged immediately after a fatality, investigators have more time to review all evidence to ensure the most appropriate charges are filed.

"Our attitude in a lot of these cases is let's get it done, let's talk to everyone," before an ultimate decision is made, Bourne said.

He said prosecutors also may want to approach the suspects and discuss possible settlement negotiations before a charge is made so the court process can go smoothly.

Patrick Orr: 373-6619