BuddyPress.org

update to make it more generic (change your theme image path as nec):

function my_new_mysteryman () {

return get_stylesheet_directory_uri() .  '/_inc

/images/my-new-mystery-man.jpg' ;

}

add_filter( 'bp_core_mysteryman_src' , 'my_new_mysteryman', 1, 7 );