we started putting two and two together. >> robert bardo was arrested this morning on a tucson freewaybecca schaeffer. >> he's extradited from arizona to california, where he's arrested for the crime. >> when i found out how rebecca was murdered, i was staggered, because i don't think at that time we thought about stalking so much. this guy followed her? this guy went to her condo, and she opened the door, and he shot her and killed her and she's dead? what? i mean, in that time, was unthinkable. >> we all went to rebecca's funeral in portland. it was a beautiful little wooden synagogue. >> it was standing room only. there were people standing outside as well. there was so much pain, and the pain i felt too was not at least from rebecca, the pain was for danna and benson, because you know this was their only child. >> my abiding memory is that danna, her mother, was in the front row. when they wheeled rebecca's casket in, they didn't put it in front of the congregation. they put it beside danna. her hand was on the casket for the entire service. she never let her go. >> for me, i was s

. >> reporter: robert bardo was 16 when he first saw "my sister sam". >> she's outgoing and bubbly and everything. >> he wrote a number of fan letters to rebecca shafer and she responded to them, by saying yours was one of the nicest i got. >> the letter confirms for him that she reciprocates these feelings for him. >> reporter: bardo became obsessed with the actress and decided he had to meet her. he took a plane from his home in tucson and went to burbank and showed up at the lot with flowers and a teddy bear. >> he was met at the gate by the head of security and was told no, you cannot go onto the set, can you not meet with her. go home. >> but basrdo would not be deterred. >> then i was told he was very agitated and very, very angry. >> reporter: it's hard to believe now, but no one alerted the police. no alarm bells went off. rebecca had no idea the danger she was in. for the next two years, she was focussed on her career, branching out into more mature roles. >> she gets a big part in a movie called "scene from the class struggle in beverly hills." ? >> my idea of taking a risk i

instead it robert bardo waiting at her door. >> he hired a private investigator in california to go to the dmv and find out where she lived. >> reporter: the young actress tried sending bardo away but he came back and shot her dead. >> and they would just hand him her address? i was ballistic with rage. >> reporter: bardo was sentenced to life in prison and now in a new interview, saying to and he feels the guilt. >> i realize what i've done and i feel a lot of tremendous guilt. >> reporter: schaeffer's family doesn't care what he has to say now but they're grateful their daughter's death prompted change. later, a new tool, social media, makes it easier for stalkers to track their victims. >> while the laws got better, stalking has not diminished. in fact, it's on the rise. >> reporter: to combat it, david, the dmv is now prohibited from giving out personal information and police depts across the country like the lapd now have anti-stalking task forces. david? >> the new edition of "20/20" is at 9:00 p.m. right here. >>> there is more ahead on this friday. the deadly dpleaccident at a