The Crown alleges that Williams had possession of the Ruger at some stage between January 1 and 4, 2018, and loaned it to Jeffries-Smith - urging him to shoot Waite.
The court heard Williams gave Jeffries-Smith a place to hide, fresh clothes, a new SIM card for his phone and coached him what to tell the police about the shooting.
During his closing arguments, Williams' defence lawyer John Holmes urged the jury not to place undue weight on drawing inferences of guilt without strong evidence. This included there being no evidence of Williams being involved in the drug scene, he said.
Holmes said the Ruger was found in a tent during a police search on January 4, 2018, but Williams was in Gisborne at the time.
Williams' earlier admissions of unlawful possession of two other firearms also did not mean automatic guilt of possession of the Ruger, which he had no knowledge of, he said.
"You also must be absolutely sure Mr Williams had knowledge an alleged murder or fatal shooting having taken place before it was made public by the police," he said.
A Crown witness gave evidence of overhearing Williams telling Jeffries-Smith, the day before the shooting to "stand up for himself" and to shoot Waite.
Holmes said other than a witness' testimony, no other witnesses recalled this conversation.
"Helping out a mate with a place to stay and SIM card is not evidence of guilt," he said.
There was a "sheer absence of direct evidence" linking Williams with the Ruger and attempting to help Jeffries-Smith to avoid a conviction for alleged murder.
On Friday, Jeffries-Smith's lawyer Mark Edgar told the jury his client felt like a "sitting duck" and pulled the trigger because he feared for his life and the lives of his family.
"Colin says when he returned to The Trap to ask for [his] car keys back, Waite yells out "you better have the f****n money or your f****n family is going to get it," Edgar said.
Faced with the "gravest fear imaginable" Jeffries-Smith made his fatal decision, he said.
Crown solicitor Anna Pollett earlier told the jury there was "no clearer case of murder" and
Williams was also "up to his eyeballs in it" in assisting Jeffries-Smith, she said.
The jury has retired to consider its verdicts.