Police gathered enough evidence against Obara to charge him in Blackman's death, and shockingly, he was also connected to the mysterious death of a young woman from Australia, Carita Ridgway, who died in 1992.
Like Blackman, Ridgway moved to Tokyo when she was 21 and began working at a hostess club. For Ridgway, hostessing allowed her to sightsee and earn extra money to put toward her dream of becoming an actress.
That was until she was dropped at a Tokyo hospital gravely ill by a man calling himself Nishita. He told doctors Carita had a violent reaction to bad shellfish, then left her at the hospital. Busy emergency room staffers had no time or reason for suspicion, but Carita's sister did.
"I asked her who this Nishita guy was and I asked her what had happened ... she couldn't answer anything," said Samantha Ridgway, who was living with Carita at the time. "All she did was put her hand out. She just wanted her hand held."
When Ridgway's parents arrived in Japan, the family's requests for an investigation into the mysterious Nishita were, they say, ignored by both the Australian embassy and the Tokyo police.
Ridgway was moved to a second hospital, and her family was told she had suffered liver failure, was in a coma, brain dead and on life support.
"We decided, you know, we can't keep her like that, so just turn it off and let her, you know, die peacefully," said Samantha. "Which it was. Very peaceful."
Carita was cremated on the day before her 22nd birthday, and her ashes were brought back to Australia, but whatever peace the family made with her death over time was shattered seven years later when Lucie Blackman's remains were found.
After an arrest was made in the Blackman case, Ridgway's family was told that the so-called Mr. Nishita, who had brought Ridgway to the hospital, was really Joji Obara, who was being charged with killing Lucie Blackman, and was suspected in administering a fatal dose of chloroform to Ridgway.
Among the evidence police found in their search of Obara's homes was a diary note that read, "Carita Ridgway, too much chloroform," and a videotape of Obara raping her.
"They could have caught him then," said Samantha Ridgway.
Obara's trial lasted for almost seven years, a length not unusual for complex cases in Japan. On April 24, 2007, the verdict was announced, leaving one victim's family in utter shock and disbelief. Obara was found not guilty for Lucie Blackman's death. "The prosecution were horrified. I mean, the Tokyo Metropolitan Police, you could hear their jaws dropping on their chest when the announcement was made in the court. They were devastated," said Lucie's father Tim Blackman."
For Carita Ridgway's family, the outcome would be different. Obara received a sentence of life in prison for her death.
"The verdict is what it is," said Sophie Blackman. "And, you know, the guy's going to be in prison for life. And that's what was always important, was a justice in that way. He would not be out on the streets. So, I think I decided quite quickly that that was going to have to be sufficient."
With two different verdicts, both families were still left with tremendous pain. "When you lose a child, there is no closure. It's just a buzz word, I suppose perhaps to make people feel more comfortable — there's never a day that goes by that I don't think about Carita," said her father Nigel Ridgway.