Very early signs of heroin use?

I have a concern about a my cousins husband, I've known him for 10yrs and he used to be very socialable and fun. Over the past 5 or 6years he has been smoking a lot of hash (morning, all day and all night) but recently he has changed a lot. His eyes are so dark underneith he looks like he has 2 black eyes, his skin is white/grey and his skin always looks damp & clammy. When ever there's a family gathering he never socialises with anyone or speaks then leave after an hour. I know he spends all his wages on 'himself' & often takes money from my cousin and he has been off work with 'depression'.
I know he smokes hash all day but can you really spend a months wages soley on hash? It's beginning to look alot more than that and I know it's nothing like pills or coke. Could it be heroin?
What are the early signs of heroin use? I don't mean like when it gets to the stealing stage ect, I mean like the very 1st subtle signs in appearance and behaviour.
No guessing or copy&pasting from web plz

Incase you hadn't noticed sherryn, I have not ASSUMED, I am only looking for some information!!!
I think it's bullshit that I'm not allowed to have genuine concern for my relatives wellfair just cos it might be outwith my control!
You're contradicting yourself by saying I should confront him then telling me that I'm on thin ice and some people are better left alone!
And yes I am an adult, are you!!!

is he wearing long shirts to cover his arms, or wearing socks when he used to not, could be covering track marks, and the change in attitude, could be an indication, but work, stress, and otehr variables couldbe affecting that. but it say keep an eye out, sounds like if he smokes that much hash, he might be apt to say **** it, and move on up the ladder

Why don't you just ask him about this? After all, it is YOU who is so interested in his well-being, isn't it? I don't know if you are an adult or not, but why would you be prying into your cousins affairs regarding her husband? Why not simply tell her of your concerns for her husband's health & suggest that they go for a check-up BEFORE you assume this is drug-related behavior. If it is, it still wouldn't be any of your business because YOU are powerless to do anything about this problem. When the person in question gets sick & tired of being sick & tired, then & only then will they seek help for their problems. Be they legal, illegal, genetic or viral! Leave it alone before you damage your relationship with your relatives. You are on very thin ice with this type of "concern"! Some people are better left alone with their own personal way of living life & this is something that you might have to learn the hard way! I speak from personal experience as a person who once used just about every type of drug known to exist! You really don't want to get on the bad side of a person who is actively using or abusing any type of substance! They usually hook up with people who are going to protect them & assist them in living out their secret lives! This is why I say that you should just stay out of it & be there for your cousin when & if she needs you for support. You'll need to learn how to bite your lip & yes, it WILL hurt. That's a part of life that no one ever seems to talk about!