Prevent search engines from indexing specific elements on a site

A website I’m working on has a team section. Every team member has a dedicated site. On the site’s bottom of each team member three other team members are displayed randomly.

Site

What happens here is that search engines index all four images. When I enter the name a specific team member into a search engine I get all four images as results. I want to show only the main image on top. So, how can I prevent search engines from indexing the three images at the bottom?