Firstly - the TECDP Intern review process is very similar to the TECDP Associate review process. An anonymous user posted an excellent write-up down below pertaining to software engineering -- beyond whiteboarding, the questions are very similar.
I learned about Cigna through a campus career fair at my college. After asking some basic questions about the company, they took my information, and eventually contacted me back for a round one interview. This was soley behavioral STAR questions - as long as you have excellent interpersonal skills, this is a breeze. Some of the questions are detailed below. Like the other user, following the STAR questions my interviewers went moderately in-depth with how Round 2 would work, and sure enough I was contacted in a week or so with details for Round 2 day (R2D). They asked for the roles and locations I would be interested in.
R2D was a little more challenging -- essentially, R2D is a six-hour business formal event composed of two interviews, presentations, and discussions between Cigna employees and past Cigna TECDP employees.
The first interview was another behavioral STAR-based session between two senior engineers. While most of my questions were related to leadership, they will test your technological knowledge but won't whiteboard you. For the second interview, I was tasked with presenting a technological achievement with 2-5 slides of information and a time limit for a Q&A panel after the presentation. (Naturally, before R2D you get time to prepare this). I was interviewed by two senior engineers, who were quite knowledgeable and respectful. It's more than likely that your interviewers will throw some challenging questions at you to make sure you have developed understanding based off of your project.
A few days after R2D concluded I was contacted with an offer. Overall, this was an excellent interview experience that familiarized me with the company mission and culture.