. >> in her 15 years at corcoran, officer diane murphy has learned just how powerful prison gangs areyou come to the prison, you have to join a gang. you have no choice. if you don't join a gang, well, you better pack up and go into the sergeant's office and tell him you're ready to leave the yard. because there's no options. you have to be in a gang. >> within these fiercely guarded activities, the most innocent active become life-threatening in a moment. >> if you're running and there's a man walking out in front of you you want to yell out track. because he's liable to proceed behind you and nail you, either with a weapon or a fist. >> somebody want to control this basketball court or that basketball court or this weight bench or that weight bench. the cos have nothing to do with that, that is amongst the inmates, the convicts. sometimes you be able to talk it out and get it settled without violence. sometimes you have to bring violence. >> this is just like on the street, you can be here today and you can be gone tomorrow. >> with violence always on the verge of exploding, the off

diane cho, abc seven news. >> randy taylor was sentenced this week to two life sentences for the murder and abduction of the virginia teenager. murphy was last seen in august in 2013 in virginia. her car was found, but her body was never recovered. investigators found one of her hairs at taylor's home. he was convicted this past may. covering metro, starting today, the silver line is now carrying passengers. where will commuters park in tysons corner? mall officials say they won't be welcome there. we have details on how the mall plans to keep metro riders out. >> there are those who think commuter parking and the silver line will work out just fine. >> i'm an optimist. >> many more are bracing. the -- the 40 stations have no garages. many of the thousands of new commuters looking for parking will instead find signs everywhere telling them commuter vehicles are not welcome. park andk they should get them all. tysons corner is making it clear that spaces are for shoppers, not metro riders. >> if an individual is in violation of our parking policy - that leaves tammy davis with one question. >> how do you differentiate between commute