In October, 13-year-old Erin Gallagher did the same, followed by her 15-year-old sister Shannon two months later.
Hannah Smith took her own life at her family home this month, just weeks after Scottish teen Daniel Perry, 17, died.
The five teens had all been abused, bullied and even received death threats on Ask.fm before they died.
Ask.fm allows users to pose questions to each other, either under their username or anonymously. Users can block those who operate under a name, but not those who post anonymously.
The majority of abusive and bullying messages are posted by anonymous users.
The site was created by brothers and internet entrepreneurs Ilya and Mark Terebin and is run from the company's headquarters in Latvia.
They would not speak to the Herald directly to answer questions about the site and issues of cyber-bullying and safety.
Instead, London law firm Mischon de Reya responded on their behalf.
"At this time, the company has no comment to make other than what was released last week in its open letter and press release of Friday 9th August," said communication and PR manager Hayley Geffin. "Currently an independent audit is being carried out on the site and its safety features."
The findings and announcement were supposed to be made public on Friday. However, the Terebin brothers said they would hold off making a statement until today, out of respect for Hannah Smith, whose funeral was held on Friday.
In their August 9 release, the Terebin brothers said they were "committed to providing a safe environment for our users".
"We are constantly working to improve our site and its safety features. We recognise the importance of acting quickly and decisively at this time to ensure our users and their parents do not lose confidence in our social network," they said.
"A team of lawyers and media specialists are currently undertaking a detailed examination and investigation of the various procedures and policies we have in place. They will report back to us with their findings and comprehensive recommendations in the next seven days.
"We are confident that taking this action is in the best interests of our users and of social networkers as a whole. We are committed to safeguarding against bullying and harassment in all forms and would welcome the opportunity to collaborate with our colleagues across the industry to do this."