On the flagpole outside the Commissioner's office there can be seen two flags flying. One is the Union Flag of Great Britain. The other is an upside down version of the flag of St. Kitts and Nevis.
The actress portraying Ricki Dacre speaks with an over the top affected American English accent that betrays the fact she is not a natural American English speaker, but likely has a natural British accent.
Ricki Lee Jones is an American singer/songwriter
As is the case in many police shows, the most damning evidence against the accused is the murderer's own admission in the final act. This is stronger than any actual evidence gathered by the protagonist.