What does "dead dropped" mean in this context?

[Torsten]

Hi,

I have a vague idea of the term "dead drop" but could you please take a look at this paragraph and let me know what "dead dropped" means here:

Probably the envelopes were not hand-delivered from these persons to Heath. Really wouldn't be any need in writing the name on the envelopes if they were. They were dead-dropped."

In that story, two police officers found those envelopes in the garbage of a suspect. Now, I guess "dead-dropped" simply means that they envelopes didn't have a sender's name and were dropped into the mailbox of the suspect?

Thanks,
Torsten

TOEIC short conversations: A cable TV customer calls technical support

[Conchita]

You enjoy detective novels, don't you, Torsten?

The Encyclopedia of Intelligence sheds some light on this:

http://www.answers.com/topic/dead-drop-2

[Torsten]

Hi Conchita,

Thanks a lot for your immediate response. You are right, I do like thrillers and the current one I'm reading for the second time because it's rather complex. What about you, are you reading any books at the moment?

Regards,
Torsten

TOEIC short conversations: Two employees talk about one of their former colleagues

[Conchita]

Much as I hate to admit it, a pile of half-read books has been gathering dust for ages, looking dejected and forlorn at being so unjustly consigned to near oblivion, waiting in vain for me to bestow something more than an occasional furtive and guilty glance in their direction.

I seem to have entered a new phase in my life, as far as books are concerned, since most of my reading is done online, these days (bits and pieces here and there) – not because we need to save trees, mind you, but rather out of addiction, I suspect. The sad part is that it's not half as exciting as reading real 'flesh-and-blood' books. Well, I'll just have to do something about it, whether I like it or not.