Death Is Disposable

Description for DEATH IS DISPOSABLE by Evan Marshall:

As New York Sanitation Department garage supervisor, Anna Winthrop thought she'd seen it all, until a homeless man she'd befriended is found murdered behind her apartment building. And Anna's taking this personally. The man had asked for her help, but was killed before he could tell her why. So now she wants answers. She immediately delves into the poor man's life, following the trail of slim clues left behind, and makes a shocking discovery about his past, only leading to more questions.

As Anna pieces together a puzzle that spans upscale art galleries, homeless shelters and encampments in abandoned subway tunnels, she realizes that her friend's life was much bigger and more complicated than she ever would have thought. But the true motive for the murder is the most bizarre revelation of all -- and makes this crime much more personal than she could have imagined.

This is #1 in A Hidden Manhattan Mystery.