This seems to be an ongoing chewed over chestnut in this case. It seems that people go 50/50 back and fourth on the subject. Some find it strange, and others dont. From my own personal experiences I can remember being Suzie's age, and having friends that would and did do things like this, and it really didn't bother me because I felt comfortable doing the same to them. Heck, I have friends I haven't seen in 25-years where I would still feel comfortable walking into their home.
On another note, I think Kirby entered the house on Delmar; after not seeing any overturned tables or other signs of foul play, she didnt feel or sense a reason to run outside and start sounding the town's bell. She basically did what any normal teenager would do in the same situation, and said: "F-EM.... I'm going swimming.
Therefore theres nothing really strange about it. Maybe that's just the way things were back then. Watch some of the old PI shows like Magnum or Rockford, and you will see people did stuff like this all the time (checking on a friend), whatnot.. McCall came to the house in the evening to retrieve Stacy's car in an attempt to teach her a lesson. Did she just take the car and go? No.. she searched the house, she deleted messages on the answer machine, she rifled through the purses, and even ransacked Suzie's bedroom, but no, no one sees that as strange, and I dont ether; because some people are just like that.
So when you couple all this stuff together, theres nothing really strange about it, when you consider the circumstances that are involved.
Now after all this, we have this other little chestnut where some seem to think that this was somesort of staged crime scene that was organized and orchestrated by some very brilliant teenage masterminds. One little genius cleaning up some glass on the porch while the other stacking some purses on the stairs leading to Suzie's bedroom inside the house.. Really???
In all probably, it really appears that this was a home invasion, and an abduction that was committed by some perpetrators that were most likely total strangers to these three women. We dont really know the how or what, but it does appear that the perps probably lined up the three purses on the stairs in an attempt to comfort the women into thinking that they were just going to be robbed. Because the perpetrators didn't take the purses, and because a great deal of money was left behind; I think commonsense would rule robbery out as a motive. Some things we do know is the fact that the perps were probably driving a van. We know this because someone (I think paper boy) saw the van sitting on the street corner staking out the Delmar house. There was also a witness who lived a couple of blocks away from the Delmar house who was sitting on her front porch, when she saw a van and observed something suspicious about it. The description of the van was very unclear, and at this point I dont really think it matters. After all these years, I think all emphasis should be placed on finding the three missing women.