Character list so far:

Alex the protagonist, son of wealthy business owner.
Celeste young widow, mother of abandoned young son, destitute addict and Alex's love interest and ex mistress of Bob to whom she had an unplanned pregnancy.
Freya Alex's sister, passionate, socially aware activist, wealthy widow of Bob
Bob Hart deceased corporate lawyer, married to Freya, had brief affair with Celeste resulting in an unplanned pregnancy.
Suzanna mother of Alex, Freya and Marcus, recently widowed.
Marcus brother to Alex and Freya, son of Suzanna, spoilt and made favourite child by his mother.

Hope that helps. It leaves it wide open for who the murderer is though.....and Death will probably show up more than once