Meaning of 足 and ブラ下げる

Question

From a blog about Death Note:

自分に付き纏い始めた何者かを葬り去るためのキラの作戦が展開されたわけですが、 さすがキラの頭脳は普通ではないと思わせるような計画の内容でした。 私なら、とにかく捜査官の顔写真と名前を入手して、自分で写真を見ながら名前を書くでしょう。 しかし、ファイルを入手する過程で何らかの”足”が付きそうですね。 まさか、自分のパソコンにデータを送ってもらうわけにも行かず、 となるとレイのパソコンを強奪するしかないわけです。 でもノートパソコンって．．．　あんなもんブラ下げていたら、結構目立つんですよね。

Context: the author is trying to analyze if Light made a mistake by killing Ray Penber, the detective that was investigating him. After finding out his name he set up a scenario where he made Ray write all the names of the fbi agents in japan investigating in a page from the death note with predetermined details of their deaths.

I think the author is saying that if he was in that case he would find a way to get the fbi agents names and photos and he himself would write them on the death note (instead of having another person doing it).

Then this sentence appears しかし、ファイルを入手する過程で何らかの”足”が付きそうですね。 which I think means It seams there's (already?) somekind of way of being carried out? attached to the method for finding the information of the agents.

Then I think he is saying that he can't get that information sent to his computer, so his only choice would be to steal his laptop. Then here:

でもノートパソコンって．．．　あんなもんブラ下げていたら、結構目立つんですよね。

but the laptop... if something like that is hanging, if would be very noticeable (suspicious?)?? if ブラ下げる is transitive who is the agent?

Answer 1

This 足 is jargon meaning "trace" such as a fingerprint, a footprint, DNA, log data, etc. It's mainly heard in detective stories. In this context 何らかの足 ("some kind of trace") refers to the log data of the hacked system.

This ぶら下げる is a transitive verb that means holding/hanging something like a tote bag. The intransitive version is ぶら下がる.