The Poet by Michael Connelly (1996) Little Brown, & Co.

A new lead character appears in this novel, Jack McAvoy, a journalist in Denver.  His specialty, murder stories, becomes ironic when his twin brother, a homicide detective, kills himself.  Jack decides to write the story to cope with his grief.  Researching the issue of homicide cops committing suicide, he discovers a disturbing fact – those who had a seemingly unsolved case, all had something in common, a suicide note that simply quoted poems by Edgar Allen Poe.  Is this really the work of a suicide killer?  And can Jack expose the truth without becoming a victim himself?