Usually, once a possible crime occurs, the police investigation is swift.

But that's not always the case, especially when a police officer is the subject of the investigation.

In one police shooting from February, involving a Detroit police officer who shot 19-year-old Raynard Burton in the backyard of a Detroit home, investigators seven months later still haven't submitted their findings to the Wayne County Prosecutor's Office.

A Detroit police officer arrested in Monroe County for drunk driving on Dec. 22, wasn't arraigned on any charges until more than two months later.

It took nearly a year for police to investigate and the prosecutor to clear two Dearborn police officers in shootings that occurred in December 2015 and January 2016.

The latest investigation involving law enforcement is of a Michigan state trooper accused of shocking 15-year-old Damon Grimes with a Taser the evening of Aug. 26 while amid a pursuit. Grimes, who was fleeing the trooper on an all-terrain vehicle, crashed and died.

A lawsuit was quickly filed against the trooper by Grimes' mother, but there's been no decision whether to charge or clear the trooper of any crime.

Wayne County Prosecutor Kym Worthy on Friday issued a statement about the investigative procedure and why police-involved cases sometimes take longer than others. She said:

Although I am prohibited from commenting on the investigation of the recent ATV fatality of 15-year-old Detroiter Damon Grimes, I think that it is important for the public to understand the procedure the Wayne County Prosecutor's Office (WCPO) follows in all police involved matters. Members of my office that will be assigned to the case have met with the family of Mr. Grimes to explain this procedure.

There a two separate and independent investigations in this case. One is being conducted by the Detroit Police Department, and other is being conducted by the Michigan State Police. The law enforcement investigations must be completed before WCPO receives the warrant request in the case. Once it is received, we conduct a completely separate and independent investigation before making a charging decision. We do this because it is important for us to take the time to closely look at the facts and evidence, so that we can be right. This is the standard procedure followed in every police involved incident that comes to our Public Integrity Unit, and it will be followed in the case of Mr. Grimes.