I couldn't find the story I was looking for but here are a few. Both TSA and CBP represented here; the CBP stories are closer to what the grandparent post describes.

These stories describe sexual assault graphically (to various degrees).

https://www.techdirt.com/articles/20110906/11065015824/tsa-a...

https://arstechnica.com/tech-policy/2016/06/woman-sues-borde...

http://www.azcentral.com/story/news/politics/immigration/201...

https://www.texastribune.org/2016/07/21/cbp-awards-us-citize...

http://www.huffingtonpost.com/entry/cnns-angela-rye-was-subj...