Dic: culprit

• About 10% of Japanese teenagers are overweight. Nutritionists say the main culprit is increasing reliance on Western fast food.

2. N-COUNT

When you are talking about a problem or bad situation, you can refer to its cause as the culprit.

.... Cobuild

• Anglo-French culpable guilty + prit ready
• culprit: French. coupable m/f

.... http://www.thefreedictionary.com/culprit