Manuel Robinson, 18, and Nicho Waipuka, 20, have been on trial in the High Court at Wellington for the murder of the gay Radio New Zealand journalist.
Cottrell suffered a shattered skull in an attack in central Wellington as he walked home from work early on December 10 last year.
A jury of seven women and five men have sat through two weeks of evidence from more than 65 Crown witnesses
Summing up the case this morning, Justice Forrest Miller said Mr Cottrell had died violently and had done nothing to provoke the attack.
"He was just walking home from work," he said.
"This is a sad case. We all have great sympathy for Mr Cottrell and his family."