For some reason , one of your crew left the organization , as a leader will you maintain the continuous relationship with him\\\\her? or forget him\\\\her?

Without a doubt that the relationship must continue with you so here comes the role of cross-fertilization of ideas and experiences, and their transition from work environment to the other, and the continuation of this relationship could strengthen links in the current working team

Thank you for your invitation ............... maintain the continuous relationship with him \\\\ her

Of course I would maintain the contact. One should never burn bridges behind.

I have faced similar situation...and I am still in touch with my boss..though the daily life we may get involved inourselves, but its good to still keep in touch with the old pals whom we worked with for long years. 

Well, there is a great difference between business and personal relationships. Hence, we should differentiate the nature of relationship that you mentioned above

There should be an one-way open channel with the employee after leaving his job if it is business related issue/ s, specially if it will affect the business positively

But if there's any kind of personal relationships, it doesn't have to interfere with the business in any way

Simply, avoid any 'Conflict of Interest' by all means

If he is an extra ordinary and hardworking one, there the leader will have contact with him, I think so

There is a saying "Never close the door behind yourself". I will keep the relationship with him/her because of mutual recources and possible business connections, as well as, knowledge exchange.

Acknowledge the view of  MR. Haytham  Thank you

Hi always, good relations should be maintained even with those expelled from the organization because they will be potential customers in the market