“I will have the support of my family, friends and neighbours to protect him.
We have to live with this for the rest of our lives,” he said.
The father, who was not named, said he would be able to handle the stress of the case alone.
“He was like my son,” he added.
A woman and three children, aged between five and 10, were killed in the attack in December, when a gunman opened fire outside a shopping mall in Nairobi, Kenya.
Nairobi police later said they were looking for a second man who they said may have been involved.
Two other people were also injured.
One of the children, whose mother was in the mall when the shooting happened, survived but was left with a broken jaw.
He is now in hospital with a skull fracture.
Other survivors said the father had tried to protect the children and their mother by making sure they were taken to a safe location.
Kenyan police have said they have not found a motive for the attack and the investigation has been handed over to the Independent Police Complaints Commission (IPCC), which is looking into the attack.
In a Facebook post, Nairobari said he did not know the children’s mother, who is a teacher, and was not familiar with her background.
It was only when she became a teacher in the city that she realised she was being targeted by a gang of people who wanted to hurt her, he said in the post.
His mother said she believed she was the victim of a hate crime.
Abu Ahmed, a police official, said police had not found any link between the attack on the children to the gang’s earlier attacks on people in the same community.
Investigators are now trying to identify the three men who were seen on CCTV footage leaving the mall and walking away from the scene of the shooting.
They are understood to be part of a gang known as the White Wolves, and they have been linked to several other crimes including the rape and murder of a 16-year-old girl.
After the attack, a group of men in the Nairobian area said they had killed and dismembered the children.
Earlier on Thursday, a local government official in Nara said they would not allow anyone to come into their area to celebrate Eid al-Fitr.
But the Nara Mayor, Yvonne Ngani, has defended her decision to close schools.
She told a news conference that people could still go to Eid schools, but she had been told that would not happen this year.
‘We will do everything’Police are urging people to report any suspicious behaviour to police.
Police said they will be monitoring the situation closely and will work to prevent future attacks.
On Thursday, Kenyan President Uhuru Kenyatta said he was “heartbroken” by the attack which had left his country “in shock”.
“We are deeply saddened by the tragic news of the murder of Nairobs children.
We are going to do everything to protect them, and we will not allow them to be forgotten,” he told reporters.
Mr Kenyatt said that his government would “make every effort” to protect Nairobanese children.