The 36-year-old was “giving back her time to the community” as a volunteer for the Tall Ships event on the day she was last seen, Aug 22, 2012.
Her partial remains were discovered in undergrowth in a forest in the Dublin Mountains last Friday.
Then it emerged that personal belongings linked to Ms O’Hara, including her Dunnes Stores loyalty card, were found in a reservoir 20km away at Roundwood, Co Wicklow.
Gardaí are investigating if handcuffs and leg restraints found at the scene are connected, but Garda Commissioner Martin Callinan said it was too early to say.
The items were recovered from the reservoir, aided by the fact the water was about 5m lower than normal.
Detectives are trying to piece together how the woman, who had left her car at Shanganagh Park, Shankill, got to Roundwood, 4km away, and how her remains ended up in Killakee mountains.
The car, a turquoise 05 D Fiat Punto, was discovered by gardaí on Aug 24, 2012.
“We are appealing to any person or persons who may have met, spoken to, or engaged with Elaine between Aug 22 2012 and Aug 24 2012,” said Garda spokes-man Supt David Taylor.
He said Elaine was last seen close to a footbridge at Shanganagh Park, at 6.15pm on Aug 22.
He added: “I’d like to paint a picture of Elaine O’Hara. Elaine was a childcare assistant, a very trusted person, very respected. She also worked part-time during the summer months in a newsagents in Blackrock Shopping Centre and was a very popular employee with her colleagues.”
On the day she went missing, Ms O’Hara was wearing navy tracksuit bottoms, white runners and a bright blue zip-up top.
Supt Taylor said it was still a “suspicious death” investigation, but stressed it was a “full investigation” and searches continued for further human remains, including the skull, at Killakee.
Mr Callinan described some speculation as to the handcuffs and restraints as unhelpful.
On reports Ms O’Hara may have met someone on an internet dating website, he said it was too early to say.
Anyone with information can ring 01 6665200 or the Garda Confidential Line on 1800 666 111.