In April 2017, a bombing took place in the Saint Petersburg metro. The explosion killed 16 people and injured 103.
Russian security services arrested 11 suspects. They were sentenced last December. All of them denied the charges. The Memorial human rights organization sees the trial as questionable.
Blog version: https://avtonom.org/en/author_columns/russia-just-fitting-terrorist-profile-will-put-you-prison
Video version: https://youtu.be/xC9f3ZOtbtk