Madison Square Murders - Memento Mori, #1

Everett Larkin works for the Cold Case Squad: an elite-if understaffed and overworked-group of detectives who solve the forgotten deaths of New York City. Larkin is different from others, but his deduction skills are unmatched and his memory for minute details is unparalleled. So when a spring thunderstorm uproots a tree in Madison Square Park, unearthing a crate with human remains inside, the best Cold Case detective is assigned the job.
And when a death mask, like those prominent during the Victorian era, is found with the body, Larkin requests assistance from the Forensic Artists Unit and receives it in the form of Detective Ira Doyle, his polar opposite in every way. Factual reasoning and facial reconstruction puts Larkin and Doyle on a trail of old homicide cases and a murderer obsessed with casting his victims' likeness in death.
Include some unapologetic flirting from Doyle, and this case just may end up killing Everett Larkin.