in front, in front of

I came across this sentence which is difficult to translate

here is my version:

"People must trust one another because they leave traces both behind and in the front."

"In the front" sounds strange at the end of the sentence.

so how about ... behind and in front of themselves?

Also I am not sure if I could use gerund instead of "because":

"People must trust one another leaving traces..."

or "considered leaving traces"?