MO is how a crime was committed and can change; signature is behaviour beyond what was needed, thought to be more stable.
Not necessarily. Many features are common across unrelated crimes, so distinctive combinations and physical evidence carry more weight.
The FBI's Violent Criminal Apprehension Program helps agencies identify violent crimes with similar characteristics across jurisdictions.
It can misdirect investigations, overlook the real offender in each case and cause distress or false hope for families.
Send a sourced summary listing similarities and differences to each responsible agency rather than publishing claims online.