Of those killed in the massacre, 42 died at the Masjid Al Noor mosque on Deans Avenue in central Christchurch, seven were killed at the suburban Linwood Masjid Mosque, and one person died at Christchurch Hospital.
An Australian man remains the only person to have been charged in connection with the attacks at two mosques in the city of Christchurch on Friday.
- > Rotherham abuse survivor Sammy Woodhouse speaks out after town linked to New Zealand terror attackBrenton Tarrant, 28, appeared in court on Saturday charged with murder and was remanded until April 5. Police said further charges would follow.
New Zealand Police Commissioner Mike Bush said he would not be ruling out the possibility of further suspects "until we are absolutely convinced as to how many people were involved".
Two people arrested after the attacks were not believed to have been involved, police said, with one released and another charged with a separate offence.
Another person was taken into custody "due to evidence collected during the investigation" but there was "no information to suggest" they were linked to the attacks, police added.
On Sunday, prime minister Jacinda Ardern said the process of returning the bodies of those killed to their families would begin that evening.
According to Islamic law, bodies should be cleansed and buried as soon as possible after death.
"It's likely to be a small number to begin with," said Ms Ardern, "It's the expectation that all bodies will be returned to families by Wednesday."
A 50th body was discovered at the Masjid Al Noor mosque on Sunday morning, with victims believed to range in age from children to the elderly.
Thirty-four people remain in hospital with injuries, 12 of them in intensive care.
A four-year-old girl taken to Starship Hospital in Auckland remains in a critical condition.
Tarrant appeared to have live-streamed the terror attack and outlined his anti-immigrant motives in a manifesto posted online.
In the video a man inside a mosque appears to say: "Welcome brother", as a gunman approaches.
Ms Ardern said her office was one of more than 30 recipients of an emailed copy of the manifesto just nine minutes before guns were fired.
"It did not include location. It did not include specific details," she said, "Within two minutes of receipt it was conveyed directly to parliamentary security.
"Had it provided details that could have been acted on immediately it would have been, but unfortunately there were no such details in the email."
A number of improvised explosive devices found on a vehicle after the shootings were defused by police.
Social media giants were criticised in the wake of the attack for not doing more to stop such content being posted on their platforms.
On Sunday, Facebook said it had removed 1.5 million videos of the attack worldwide in the 24 hours after the shootings, 1.2 million of which were blocked at upload.
Mia Garlick, of Facebook New Zealand, said: "We continue to work around the clock to remove violating content using a combination of technology and people.
"Out of respect for the people affected by this tragedy and the concerns of local authorities, we're also removing all edited versions of the video that do not show graphic content."
Mr Bush said the gunman had obtained a legitimate firearms licence in 2017 in New Zealand, adding that it was "quite obvious" he had "modified a category A firearm".
Ms Arden has vowed to change the country's gun laws in the wake of the shooting spree.
Australia's Nine Network television on Sunday broadcast an interview with a woman and a man who it says are a grandmother and an uncle of Tarrant.
The woman, identified as Marie Fitzgerald, said: "It's just so much for everything to take in that somebody in our family would do anything like this."
She added: "It's only since he travelled overseas, I think, that the boy has changed completely."
The uncle, Terry Fitzgerald, said: "We say sorry, for the families over there, for the dead and the injured, yeah we just, can't think nothing else, just want to go home and hide."
Officers will stand guard outside all mosques across the New Zealand that choose to open their doors, while police have promised an increased presence across the country as people return to work and school on Monday.
A fund set up to help victims' families and those who suffered injuries has raised over 4.3 million New Zealand dollars (£2.2 million).
The page on the site givealittle was created by a council of victim support groups.
The council said it had been overwhelmed with the number of donations, adding it would need to create a formal process to distribute the money.
British security sources said there were no apparent UK links to the attack.
A 24-year-old man from Oldham, Greater Manchester, was arrested on Saturday after posting comments online supporting the slaughter, Greater Manchester Police have said.