How do police investigate a rape or sexual encounter?

Police investigate rapes and sexual violence encounters by:

http://www.policeone.com/police-products/investigation/evidence-management/articles/509858-Investigating-Rape-Crimes-Part-1-Guidelines-for-first-responders/


"From a law enforcement perspective, we want to quickly arrest the perpetrator using investigative techniques that ensure a conviction and a process that causes the least amount of psychological trauma to the victim. More likely than not, this will begin with a call from the victim to police headquarters. How civilian-police dispatch or other communications personnel handle this initial contact proves critical. Depending on the variables presented in the initial contact, police administrators should ensure personnel do the following:"

1) Ask the victim whether she has sustained serious physical injury and needs immediate medical assistance. If so, dispatch an ambulance;
2) Ask the victim if she can identify or describe the suspect. Follow protocol relative to providing this information to patrol units;
3) Immediately dispatch a patrol unit to the scene;
4) Tell the victim to wait for the police to arrive if she is in a safe location;
5) Instruct the victim not to alter her physical appearance or touch anything on scene; and
6) Advise the victim not to was or douche before she undergoes a medical examination.

"The natural instinct of rape victims is to wash, douche, change clothing and use other self-help mechanisms. First-contact personnel should do everything possible to ensure the victim does not doe this. In addition to the location where the rape actually took place (or in the case of an abduction, the point of contact and release), the victim is the crime scene. Although most forcible rape cases are legitimate and investigators should proceed under that assumption, investigators do have a responsibility to those falsely accused. We can best fulfill this responsibility by conducting a thorough investigation. Unlike many other crimes, convictions in rape cases may require corroborative evidence in addition to the victim’s testimony in court. This makes the proper gathering and documentation of physical evidence absolutely essential."

"In addition to following normal procedures in protecting primary and secondary crime scenes, one of the first responders (preferably a female officer) should conduct a preliminary interview with the victim in private to determine if she knows or can identify the person who raped her. The officer should obtain a physical description of the rapist and ask the victim to explain what happened. The investigator, a rape counselor, or another care provider will conduct a detailed follow-up interview in a setting most comfortable to the victim."

Police also (obviously) take note to the crime scene as well: Here are some steps in ways police go about searching the crime scene.

http://www.policeone.com/police-products/investigation/evidence-management/articles/509858-Investigating-Rape-Crimes-Part-1-Guidelines-for-first-responders/

Goals for Searching the Crime Scene:

Remember: The crime scene encompasses all areas in which people connected with a crime were located shortly before and after the crime. Both the perpetrator and victim moved through physical locations in order for crime to be committed, while the crime was committed and after the crime was committed. In searching a crime scene, we operate under the premise that whenever human beings interact with any inanimate or animate object, something is either taken away or left behind. The objectives of the search of a crime scene in a forcible rape case are the same as in any other major case:

1) Reconstruct what happened and establish that a crime occurred;
2) Identify, document and collect evidence of what occurred;
3) Link the victim and the suspect to the scene of the crime;
4) Identify and locate any witnesses; and
5) Identify and apprehend the person(s) who committed the crime.