He helped in the recruiting of the other members, and he was recruited because of his past (his father) and his intelligence. The members were recruited and then they were members it showed no special initiation process.
Before Derek went to jail, even when he was in jail the members of the DOC looked at him as a god. He organized the crimes, which consisted of vandalism mostly; the one act of crime it did show was their gang running into a grocery market that was owed by Koreans and Mexicans worked there. They damaged the food, store, beat up and harassed the employees. In this gang of DOC drugs were not apart of it. They said marijuana was for "niggers." The members of the DOC all had shaved heads, and had either nazi sign, or the letters DOC tattooed on them. They hate anyone who is not white protestant. They have girls around and treat them normally. Derek has a girlfriend who is always with him and seems to get off when he acts tough. The police do not play a huge role in this movie except for when they arrest Derek, and when they are notified of his release. .
When Derek is released from prison his entire family comes to pick him up. His family consists of him, his mother, and his younger brother Danny and his two younger sisters. He treats them all very well accept the night of the murder. He snaps at the dinner table and becomes very violent with his sister and mother. Later this evening is when he kills the two black guys.
When Derek is released from prison everyone in the gang assumes things will go right back to the way they were. They even praise him more because of what he did. Seth who is a fellow member comes over to the house soon after Derek returns and he treats Derek's sister and mother horribly. He also makes comment about Derek's hair because it is now grown out. He then invites him to a party that is being thrown at Cameron's place in honor of Derek's return.