Plot summary
The shooting murder of married auto dealer Joseph Sabo ( Kent Cassella ) initially perplexes Detectives Logan and Barek. However, they discover that he, and other cheating family men, were being blackmailed by phony paternity claims of a self-involved and exploitative mother Danielle Quinn ( Elizabeth Berkley ). After they arrest her, the detectives discover that Danielle's seemingly meek and maternal sister Claire Quinn ( Heather Burns ) is having an affair with Danielle's lawyer, Declan Pace ( Christopher McDonald ). This leads them to eventually uncover that Sabo planned to kill Danielle instead of paying her when she ambushed him instead, but it was a plot hatched between Claire and Pace to gain custody of Danielle's child after she would be arrested for the murder.
Credits
Adapted from Wikipedia contributors, Law & Order: Criminal Intent season 5. HTML formatting and reference markers removed.