I’ve read through most of the Dead Sea Scrolls (in English translation) before. A lot of the material is highly fascinating since it appears to have been written by people (or a group of people, most likely the Essenes) concerned with the end of times. Most of the documents are written in the style of the OT prophets. The one fragment which scholars are highly interested in is called “The War Rule” which is a six line fragment concerning either a “Piercing Messiah” or a “Pierced Messiah”
Read more here.
Due to the prophetic nature of these books, as in the above instance, many people and scholars regard them as just as authoritative as any other prophetic book; however, since they were only first discovered in the mid-20th century, their value is secondary to what is already contained in Biblical canon.