How to get roles for given user id

I need to pull all the roles for given user ID. I can see there is function call Get User In Role which I can combine with following code to get my answer only If I can pass user id NOT current user.

for(var counter=0; counter<RolesList.Length; counter++)

{

RoleTile = RolesList[counter].Attributes["roleName"].Value;

if(RoleTile!=null)

{

//var IsUserExistInListedRole = Me.Case.WorkingCredential.IsInRole(RoleTile);

???????????????????????????????????????????????

if(IsUserExistInListedRole=true)

{

if(ListedUserRolesTitle.Count=0)

{

ListedUserRolesTitle = "(" + RoleTile + ",";

}

else if(ListedUserRolesTitle.Count!=0)

{

ListedUserRolesTitle = ListedUserRolesTitle + " "+ RoleTile;

}

}

}

}

ListedUserRolesTitle = ListedUserRolesTitle + ")";