var User = mongoose.model('User', new Schema({data}));
var DeletedUser = mongoose.model('DeletedUser', new Schema({data}));

exports.postDeleteUser = function(req,res) {

    var conditions = { '_id': req.params.user_id };

    // Create the new deletedUser object to add to
    // the DeletedUsers collection
    var deletedUser = new DeletedUser();

    User.findOne(conditions, function(err, user) {
        if (!user) {console.error(err);
        } else {
            // Copy over data to the new deletedUser object
            for (prop in user) {deletedUser[prop] = user[prop];}

            // This is where I save the deletedUser to the
            // new collection.
            // ** This is not executing ** //
            deletedUser.save(function(err) {
                if (err) {
                    console.error(err);
                    renderViewUser(user['_id'], 0, req, res);

                } else {

                    // However, this delete from Users *is* working
                    User.find(conditions).remove(function() {
                        res.redirect('/');

                    });
                };
            });
        };
    });
};