"I convey the message of love and support on behalf of New Zealand to all of you", she said.
Muath Elayyan, Mohammed's brother, told the Associated Press his brother helped establish the mosque a year after arriving in New Zealand, where he teaches engineering at a university and runs a consultancy.
A disabled man on crutches, accompanied by a lady with flowers in her hands, was also seen come to the spot. "He enjoyed freedom there and never complained about anything", Muath said.
Wearing a black scarf, Ardern hugged members of the Muslim community at a Christchurch refugee centre, saying she would ensure freedom of religion in New Zealand.
The court was closed to the public over safety concerns, however a number of people gathered outside ahead of his appearance, including a man who told reporters his father was one of the victims.
Over the weekend Palestinians in the West Bank and Gaza held vigils to honor the victims of the massacre, in which 49 people were killed.
Tarrant is expected to face additional charges and two others are in custody.
50 people died after a gunman opened fire at two mosques in New Zealand during midday prayers on Friday.
New Zealand Police Commissioner Mike Bush announced the latest death in a news conference Sunday.
‘Blood was splashing on me’: Witnesses describe horrific New Zealand mosque attack
The Archbishop of Canterbury posted on Twitter: "Profound sympathy for the victims and relatives of the New Zealand terrorism". Dunedin is a city near the southern tip of New Zealand, around 225 miles from Christchurch .
The video showed a man driving to the Al Noor mosque, entering it and shooting randomly at people with a semi-automatic rifle.
She also sent a message to American politicians given the countless shootings claiming lives in the US, writing: "America take note!"
At least 49 people were killed in Friday's attack.
Two other people have been arrested in connection with the terror attack, and they remain in custody as police conduct an ongoing investigation as to their possible involvement.
They said they were saddened by the "senseless" attacks.
Footage of the attack on one of the mosques was broadcast live on Facebook, and a "manifesto" denouncing immigrants as "invaders" was sent to politicians and media outlets and posted online via links to related social media accounts.
Ardern said Saturday that she had met with relatives of the victims and their "key concern" was to have access to their loved ones' remains for burial.
The Church of Jesus Christ of Latter-day Saints' Pacific Area Presidency also released a statement of support for Muslim communities and all others impacted by the Christchurch shootings.
"But that arrest was tangential to this matter and we do not believe that he was involved in this attack either", he said.
When asked what he thought of the prime minister suggesting there should be a change in New Zealand's gun laws, the police commissioner said he was "happy to hear" that. He had no criminal history in New Zealand or Australia and had not drawn the attention of the intelligence community for extremist views.