OW search--You can start by doing a google search, then see if your lawyer can do this. If not, then a PI.
I did this over a year ago but it can be expensive.
The Bomb: 08/05 H moves out: 06/2006 H moves back: 01/07 & Out again: 01/07 H moves back: 03/08 & Out again: 04/08 H moves back: 05/09 & Out again: 07/09 Divorced 08-12 Kids: 22, 20, 19