The man who said he saw accused killer Teddy Munet shoot William “Billy” Fallau in the back of the head in Kawainui State Park Reserve two years ago wants immunity from prosecution for anything he might say when he testifies in Munet’s trial.

Munet, 31, is scheduled to stand trial in state court next month for murder, using a firearm to kill Fallau, being a felon in possession of a firearm, and carrying a firearm without a permit. He pleaded no contest Wednesday to possessing methamphetamine and drug paraphernalia when police arrested him in Fallau’s murder.

Fallau, 29, died from a gunshot wound to the back of his neck.

The prosecutor’s key witness is expected to be Kaipo Octubre.

Three days after hikers found Fallau’s body in Kawainui Park on July 19, 2012, they arrested Octubre for driving without a valid driver’s license. The arresting officer said he received a report of a driver speeding and swerving on Kamehameha Highway in the Kaaawa-Kualoa area.

The caller also gave police the license number.

The officer said he initially was going to give Octubre, 31, a citation but arrested him instead when he learned that Octubre had three convictions of driving without a license. Police transported Octubre to the Kaneohe station and transferred him four days later to HPD’s headquarters downtown.

While there, police said, Octubre gave homicide detectives a statement about Fallau’s murder. Octubre also later testified in front of the state grand jury, which indicted Munet in Fallau’s murder.

Police arrested Munet July 24, 2012, at the Fallau family home in Kaneohe. They said a witness told them he was with Fallau and Munet at the park when for no apparent reason and without warning, Munet drew a pistol from his pocket and shot Fallau.

Deputy Prosecutor Rodney Veary told Circuit Judge Glenn Kim Wednesday that Octubre waived his privilege against self-incrimination when he gave police a statement and testified in front of the grand jury. And besides, nothing Octubre said to police or to the grand jury is self-incriminating, he said.

According to Octubre’s grand jury testimony, Kim said, “three people went in (to the park) and only two came out.” He said anything the prosecutor wants to ask him could be incriminating.

Kim, countering Veary, said Octubre will have the right to invoke his right not to incriminate himself during Munet’s trial because he did not waive that privilege with police or the grand jury. That’s because Octubre did not have a lawyer to apprise him of his rights, he said.

Kim told Veary that if the state intends to grant Octubre immunity, he needs to do that before the trial starts.