Terrible End result to runaway...help with Texas law needed please.?

[Bret]

Two nights ago my wife's nephew, who we have had legal guardianship over for the past few weeks, decided to sneak out his bedroom window after being grounded earlier in the evening. This happened about 10:30pm. We looked for him until close to midnight before calling the police and filed a runaway report. He came back to the house at approximately 4:00am and passed out. He woke about 8:00am when my wife discussed the matter with him and attempted to find out where he had been. He gave her a story after about an hour. He dressed and cleaned up and walked out the front door. My wife went to the door to ask him a question and he was gone again. The police were again notified. They told her there was still a runaway report still active and they would leave it that way. Last night we notified the police again to get an officer to actually come out for us to talk to them about this situation and to give them some more information including where we felt like he was. We passed the information on to the police and they said they would check into it. This afternoon we were notified by detectives that the boy was with another teenager and they had stolen a pickup. The police found them and ended up in a pursuit. The pursuit ended with the boys crashing out after running a stop sign and hitting two other vehicles driving down a crossing street. Both of them exited the vehicle. The passenger got away but the driver was caught. The driver is her nephew. Fortunately, there were no life threatening injuries but the innocent people were hurt. We had been constantly looking for her nephew since he left yesterday morning. I have since found out that he was in fact at the place we felt he might be last night when we passed that information on to the Officer. They had not checked out the information. We were attempting to help her nephew get his life back in order after being in legal trouble throughout his teenage years. He volunteered to come here with that in mind. His Mother and Stepdad have been unable to handle him. The first few weeks were fine. The last week spiraled out of control. These events have been happening as we were also making contacts with several organization trying to get him help. I need to see what I need to do now. He's in jail and needs to be there. I can see several people coming after me now as a result of the crash since we are legal guardians. His parents have offered to take responsibility but they don't have anything. We feel like we have opened our home to a foster parent situation and will now face legal battles as a result. This is even more frustrating since we feel like this may have been avoided with help from the police last night. Any information would be greatly appreciated. Thanks for your time.