(CBS/AP) SAN JOSE, Calif. - Antolin Garcia-Torres, the man arrested in the disappearance of Calif. teen Sierra LaMar, had been under surveillance after his DNA linked him to the case in March, police said Tuesday.
Garcia-Torres, 21, wasn't arrested after his DNA first surfaced in March for numerous reasons, including the possibility that he might lead authorities to LaMar, 15, said Assistant Sheriff Pete Rode.
"At some point, I'm sure he became aware that we were watching him," Rode said, noting that Garcia-Torres was monitored going to work, at home and hanging out with friends.
"You don't want to lose him, but at what point in time do you risk having him flee and leave the state and possibly the country?" Rode said. "We did not want to take that chance."
Garcia-Torres had been under 24-hour surveillance since March 28. His vehicle was seized on April 7. The DNA evidence used to arrest him also links him to at least one assault in March 2009, Santa Clara County Sheriff Laurie Smith said.
Garcia-Torres' arrest came after lab results determined that LaMar's DNA was in his car, according to Rode.
Since LaMar disappeared on March 16, volunteers and authorities have searched fields, open spaces and reservoirs near Morgan Hill, a semi-rural community of 40,240 on the fringes of Silicon Valley. The Santa Clara County Sheriff's Office announced Tuesday that searches in reservoirs and waterways in the area will begin once again this week.
Garcia-Torres could be arraigned as soon as Thursday.