One is an Institute of Technical Education (ITE) student, while the other is a middle-aged, small business entrepreneur.
Melvin Teo, 17, and Mr Delson Moo, 42, are the duo believed to have been questioned by the police last week over a recent alleged hacking of an Istana webpage, The Straits Times learnt yesterday.
On Tuesday, the police did not identify them but revealed that two suspects were involved in the Istana cyber intrusion, along with two others who allegedly hacked into the Prime Minister's Office (PMO) website on the same day - last Friday.
The two pairs are not connected to each other and did not act in concert but they had "exploited a vulnerability of those sites to display pages from other sources", according to the police.
Checks by The Straits Times found that the pair who are connected to the PMO incident are brothers, Mohammad Asyiq Tahir, 21, and Mohammad Azhar Tahir, 27. Both were arrested and have since been released on bail pending further investigations.
Melvin and Mr Moo were not arrested but continue to assist with investigations into the Istana hacking.
None of the four men is connected to James Raj Arokiasamy, the alleged hacker said to be behind the "The Messiah" pseudonym, according to court papers.
When contacted yesterday, Melvin confirmed that he had been questioned by the police about the Istana hacking, but refused to comment further.
Mr Moo also declined to be interviewed when approached at his office in Ubi Crescent but did not deny that he had been questioned by the police.
The businessman had described himself in a blog as a "doting father" of a boy and said he graduated with an IT degree.
He also said he had a "doctorate in the University of Society" - a self-made title he gave himself for "immersing myself in the workforce since I was a young lad".
Official records show that Mr Moo is a director and shareholder of an online store that sells baby products and women's clothes, and two IT-related firms, all of which are run from the Ubi Crescent office. He and Melvin are believed to be Facebook friends.
Like Mr Moo, Melvin writes a blog and is an active user of Facebook and Twitter. But his Facebook page was taken down last night.
Before it was removed, Melvin's Facebook page featured two caricatures of himself, which were similar to the one that apparently appeared on the Istana's website with the words, "Melvin Teo For The Win", when it was hacked last week.
The former Pei Hwa Secondary School student describes himself as a car and computer enthusiast on his Instagram account, which was filled with images of different cars and computer parts.
In September, he posted on his blog that he had started a small project to custom-build a computer for gaming after learning how to do so from watching YouTube videos.
The Istana hacking incident was flagged by the police on Tuesday - the same day James Raj was charged in court for hacking into the website of the Ang Mo Kio Town Council on Oct 28.
The 35-year-old was identified for the first time then as the alleged hacker who had used "The Messiah" moniker. Apart from facing charges under the Misuse of Computer and Cybersecurity Act, the runaway drug offender - who had been in hiding since 2011 - also faces three charges for drug consumption.
He has since been remanded at the Institute of Mental Health for psychiatric evaluation for two weeks, during which he will not be allowed access to any third parties apart from medical personnel. Third parties include the police.
Meanwhile, lawyer M. Ravi yesterday filed an application asking for James Raj to be granted immediate access to him. The application will be heard in the High Court tomorrow.
The Attorney-General's Chambers, responding to Mr Ravi's application said: "Our position in the High Court will be the same as in the Subordinate Courts.
"We will protect the investigation process and strongly oppose any access by counsel while investigations are ongoing."
Additional reporting by Selina Lum