While tribal police recover 90 to 150 stolen cars a month on the reservation, other law enforcement authorities are frustrated by inability to pursue the thieves. "They're driving onto the reservation knowing that we can't touch them," said Arizona Department of Public Safety spokesman Andy Vidaure. Gila River Lt. Greg Barnargas said many of the three to five cars a day recovered on the reservation were stolen in Chandler because of the proximity to the reservation and are used for joy riding. "A lot of the kids that steal the cars are Indian kids that live up here, and they go off the reservation to steal the cars and bring them back here and it's just a case of joy riding," Barnargas said. Ten or 15 years ago, car thieves from the reservation mostly were stealing cars to strip them and sell the parts, Barnargas said. Now, most are members of gangs - many of which exist solely for the purpose of stealing cars. At more than 80 miles long and 40 miles wide, "it's a very large reservation and a wide-open area that gives a lot of opportunity to these car thieves to come out and hide them out in the desert."