He said there was a possibility there were witnesses who had not come forward because they were scared or intimidated by the prospect of being cross examined.
He asked any potential witnesses to be brave and talk to police.
"If a new witness or new evidence will come out I think the Crown will reopen this case. I hope ... somebody or some good people will have seen something near here," he said.
"Especially the people who live near here, they surely saw something."
Mr Chen, whose younger brother Peter stood silently behind him during today's press conference, said he wanted to inform the public about the details of the case now it was no longer before the courts.
Mr Liu's lawyer Michael Kan told the trial the Crown could not prove beyond reasonable doubt where, when, how or why the victim was killed, and the jury agreed.
Following the verdict, Justice Sarah Katz discharged Mr Liu, who has spent the last 10 months on electronically-monitored bail.
It was then revealed the jury had not heard some evidence from the Crown because Justice Katz ruled the evidence could prejudice the jury against Mr Liu.
That included information about a phone call between Ms Chen and a friend in the days before her death, in which Ms Chen allegedly said Mr Liu would be "the one who kill me" if she was found dead.
Philip Chen said today that the family hoped the case could be reopened.
"We all the family of Cissy feel it was very unfair and we could not bring justice for Cissy."
Mr Chen said he felt he had not brought his sister dignity after her death.
She had now been laid to rest by her family.
"We buried her in New Zealand in Auckland because Cissy really liked New Zealand. So we want to satisfy Cissy's soul."
However "Cissy's soul can not rest in peace" until someone was found guilty of her murder, Mr Chen said.
"All members of my family are really hurt."
Mr Chen said according to his beliefs, Ms Chen's soul would have returned home on her birthday.
"Chinese people, we believe the soul will come back home seven days after dying. That was November 12. That was also Cissy's ... birthday."
Mr Chen said he was not yet sure when he and his brother would return to China.