Simplify the following text for a Grade 9 native English-speaking person.
Original: In 1994 and 1995 , he conspired with McVeigh in the planning and preparation of the Oklahoma City bombing â `` the truck bombing of the Alfred P. Murrah Federal Building in Oklahoma City , Oklahoma on April 19 , 1995 which claimed the lives of 168 people including 19 children .
Simplified: Terry Lynn Nichols ( born April 1 , 1955 ) is a U.S. Army veteran who was convicted of being an accomplice of Timothy McVeigh , the man convicted of murder in the bombing of the Alfred P. Murrah Federal Building ( Oklahoma City , Oklahoma , April 19 , 1995 ) , which claimed 168 lives .