SOLVED. Crime Thriller - Book Open With a hostage situation, domestic violence, protagonist watches through a sniper at victims - wife and a child. [s]

[Yugesh]

The novel opens as mentioned in the topic. The hostage situation ends with the death of victim's husband who is holding them hostage. But I dont remember how he dies, but the protagonist suspects foul play on his death.
I dont remember anything what happens in the middle except for the end, which is a twist ending.
Spoilers ahead -
The twist is that the victim's father is a rich guy and goes at great lengths to hide a rare medical condition which runs in his family and which ultimately is uncovered by the protagonist and ends up proving that the victim's father is her child's father.
May have read this book in 2015-2017.

[AdoraBelle42]

The beginning with the sniper watching a hostage situation reminds me of Lisa Gardner's Alone but I'm not sure if it had the right ending...

[Yugesh]

Yup its Alone , just found out myself. The ending is slightly different from what I posted - that the child has a rare genetic disorder which results only because of incest. And its the victim's father in law who is the father of the child.