Lokesh ji, not necessarily DK's work. Since this whole thread is in free-flowing CT mode: I suggest that it could be her dad's work that has somehow irked Washington. Uttam Khobragade has been an IAS officer since 1984. His "official" appointments have included, from most recent to least recent:
1) Principal Secy, Tribal Development Dept. (2010-present. What are the odds of his having run up against American EJ orgs operating in Tribal regions?)
2) Gen Mgr, BEST (Mumbai Electrical Supply and Transport)
3) Mng Dir, MH State Road Transport Corpn
4) VP, MH Housing & Area Development Authority
5) Commissioner, Food & Drug Administration
6) Collector/DM, Greater Mumbai
7) Mng Dir, MAFCO Ltd
Jt. Secy, Revenue and Forest Dept.
At least in terms of #1, and possibly #5, it is easy to imagine how Mr. Khobragade might have run afoul of US interests.
Of course, there is always the possibility that his actual job has nothing to do with his publicly listed postings... and that he might have annoyed, alarmed or threatened the US in discharging those actual duties.
As Lokesh ji observes, Khobragade's daughter will not be allowed to return to India due to confiscation of her passport by US authorities. Now wouldn't that be a classic way to pressure an opponent whose investigations were getting too close for comfort... by holding his daughter hostage (after having shown, through strip-searches and other public humiliation, how far they are willing to violate her?)
Looked at from this perspective: Maid and her family may just have been patsies (arranged by the CIA through EJ proxies) to provide a pretext for them to grab Devayani.