Vengeance Out of the Shadows by David Peretz
In successive weeks, two New York landlords have been shot to death, one in Central Park and one in Brooklyn. Could these be the acts of a disgruntled tenant, a business rival, or is there a serial killer out there? Ross Cortese calls on Detective Ruth Wilson, formerly a profiler with the FBI, to join the squad and assist with the investigation.
Meanwhile, Doschenko, an ex-KGB assassin, has been on the run from Interpol since Ross brought him down from near the pinnacle of power by foiling an attempted coup in Vienna. Fulfilling a contract killing in Oman, Doschenko is given the green light by his handler to come to New York, via Canada, for another assignment. It is the opportunity that he has been waiting for--to extract revenge by inflicting maximum pain on Ross and those he loves.