HONOLULU -- A jury heard a story on Friday about how a man haunted by one murder may have helped solve the death of Japanese visitor Masumi Watanabe.

Prosecutors said that building the case against Kirk Lankford was an example of great police work, but they said the first big break in the case was the result of an amazing stroke of luck.

"I feel that I had God's arm around me," witness John Thoma said in court.

Thoma had just prayed the way he had been taught by his friend Lin Hannon. She was murdered at Kahana last February, two months later, at midnight, not far from her memorial; he spotted a man with a flashlight digging.

"I thought he was the one who had murdered my friend," Thoma said.

Thoma identified that man in court as Lankford.

Lankford is on trial for the murder of Watanabe, who disappeared in April. Her body was never found.

Thoma's suspicions about a different murder led him to confront Lankford, who told him he was looking for a lost gold chain.

"I said, 'You know that sounds like bull. Let's see some ID.' He said he didn't have any," Thoma said.

Lankford fled, but Thoma carved his license number into a road marker. He called the investigator on his friend's case, who was also looking for Watanabe.

"I got there and sure enough I saw a freshly dug hole," Detective Randal Nakamura said.

Within days detectives had much of their case against Lankford because of a homeless man, who the prosecutor had worried drugs would have muddled his memory.

Thoma was such a good witness that the defense barely cross-examined him. The defense is hinting that Lankford will claim he accidentally killed Watanabe and tried to cover it up to protect his $75,000 job.