Options;
$3.50 - Macro trawled the camera footage and chased everything down and they got a break
$3.50 - The Commodore fibres. Macro followed this through which lead them to Telstra and then to BE
$6.00 - Some sort of DNA match. Maybe BE was arrested on something unrelated or maybe a family member was charged with something?
$6.00 - Someone close to him discovered something (victim property, something online) and contacted Macro
$51.00 - Macro monitored WS and in conjunction with ISPs tracked everyone down, inc. people using VPNs etc
A massive long shot but a number of unidentified people have been identified through chasing relatives dna through ancestry.com. Lori Ruff being the most prominent.