Civilians decide their own fate and set the scene for LEOs to adhere to.
It is paramount that all Officers maintain a high standard of professionalism at all times towards other officers and especially towards civilians (regardless of how the civilian may be treating you). Verbal slander from civilians where no direct threats of harm to your person or others are made is not arrestable under any circumstances.
Do not be immediately confrontational to suspects on scene, usually they are far more willing to communicate and be co-operative if the officer is treating the suspect with the same amount of respect as they expect themselves. This also prevents you from escalating a situation - this approach should be attempted in all situations unless the suspect poses an immediate threat to safety.
Identify yourself as a peace officer with your name and rank.
Evidence is paramount in determining wether or not an individual is guilty of the crime you suspect them of committing.
A suspect is innocent in proven guilty, evidence is the key determinant in proving the suspect as guilty, or not guilty.
Ask any eye-witnesses (if the eye-witnesses you ask are locals, aka AI, then you may ask for a response from the suspect via /meall).
Review Camera footage from inside the building or exterior cameras from surrounding buildings if available (via a physical camera system triggered when there is a nearby 911 call and/or gunshots).
Question/Interrogate suspect(s) this can be done at a scene or in a more formal setting in the interview rooms of Stations however in both cases the Miranda Rights must be read to the suspect before proceedings with questioning.
Search the area, suspect person or vehicle for any physical incriminating evidence (if probable cause allows for it, otherwise you must get consent to search a person and/or vehicle).
GSR (Gun Shot Residue) Swabs given consent or probable cause.
Breathaliser Test
Evidence must be handled with care in order to not adulterate any DNA samples or infringe on the chain of custody. Evidence is to be collected with latex gloves and swiftly stowed in an evidence bag to be taken to the local Office's evidence room.
When asking for identification, ensure that you ask in courteous manner and explain to the suspect the circumstances in which you are permitted to order they give you their legal identification (e.g traffic stop, detainment, arrest, etc). If you get the civilian ID, but they don’t provide you with the name on it, ask them to verify the name on the ID verbally, this also helps determine if the given identification could be fraudalent (fake or stolen).
A given suspect "description" helps narrow down the features you are looking for when searching for a suspect. However, an individual matching suspect description is only enough to detain in order to gather further evidence unless the person(s) match the given description explicitly.
The same is true for given vehicle descriptions, unless accompanied by a known licence plate.