Ideas can not be protected, only the implementation of the idea. Anyone can do a Whodunnit game and given the nature of such a game they are likely to have interrogation sequences. If the code, art and other assets are original then that is legal.
Also just because games have a similar topic that doesn’t mean that one is necessarily a copy of the other. Especially when both are inspired by the same established genres from film/books/board games. If you read the Kotaku piece you linked to and the reviews of Blue Toad Murder Files (http://www.eurogamer.net/articles/blue-toad-murder-files-review) you will see that they are very different games. The Wideload game is a selection of arcade mini-games, whereas the Relentless title focuses on more cerebral challenges ranging from "logic teasers about moving sacks around or organising bees around flowers, to maths and word puzzles where you crack basic codes and work out how many guests are in a hotel, along with a few based on visual observation under difficult (often rotating) circumstances."
Just because two screens that serve the same purpose happen to look similar that doesn’t mean the whole game is a rip off. It’s important to delve a little deeper before claiming foul play.