Question About Nick Styles Promotion

I have seen Richocet several times on tv and dvd.
So my question is about the promotion of
Officer Nick Styles from patrol cop to detective.
I don't work in law enforcement nor the legal
profession so does the DA of any large city
like Los Angeles have the power to promote any
cop to detective? Not implying that the scenario
was unrealistic just wondering if any DA has
such authority. Have always understood that
promotions are done internally within the
police force especially in a huge city like
LA. Patrol cops must take and pass a written
exam to be considered for assignment to the
detective division. And not all those who
pass will necessarily be promoted/assigned
to become a police detective. It depends on
how many billets for detective are open.
Just wondering. PS Have always loved actress
Linday Wagner since her days as the original
bionic woman. She was so cool here as
DA Priscilla Brimleigh!


Lorenzo Sunny Florida

I'm James "Sonny" Crockett!