Why did Vance say he interviewed the Sandy Hook shooter's "co-workers," and "former students?"

Lt. J. Paul Vance, updating reporters:

"The secondary crime scene, as I told you, was a crime scene that was discovered pursuant to the investigation. Once we had a tentative identification on the suspect, we began doing a great deal of work. Again, peeling back the onion--everything we could find out about that suspect, including and not limited to relatives, friends, co-workers, um former students...location of residence, and all those areas, people had to be--people had to be interviewed, and all those areas had to be examined. Hence, that caused us to discover the secondary crime scene, which was a private residence with a sole female, deceased."

[link to audio.wbur.org]

There are a number of things that stick out here.

First off - co-workers? Did one of the suspects have co-workers? Vance makes it sound very much as if he did.

Secondly, former students? Students of what institution? Is he talking about Newtown High School? Cops don't even know the suspect's address, but they know he is a "former student" and are immediately able to find his former classmates? That's just bizarre. It may have something to do with reports that the purple van went to the high school first. Possibly the studetns at the high school 12/14 who reported the van recognized the occupants as older, former students, and told Vance the names of some of the van group's old buddies at the school? Maybe those high schoolers who reported the van, in fact, are the ones who reported the occupants as armed, and dressed like nuns. Maybe the reason they knew what former students Vance should talk to is because they heard of the plot ahead of time, and knew it was some 20-something ex-Newtown High students who had been talking about "getting famous" or something to that effect.

Thirdly, Nancy Lanza's car was allegedly at the high school. If they had a tentative ID on a dead Lanza boy, and Nancy Lanza's car sitting in the parking lot, what the hell do they need to interview a bunch of former high school students and co-workers for? Wouldn't you just dispatch an officer at top speed to 39 Yogananda the minute you run the plate? I mean, they spotted weapons in the vehicle upon arrival (Penna's story). Is there any question this is a suspect vehicle, and is there any question that someone should immediately go to the residence?

If you know all these people you should interview--family, co-workers, and former students--then you sure as hell know who you think you have lying dead there, and you just drive to his house. His mom's car is right there in front of your eyes, filled with guns.