It comes as Ms Mary Temas, the mother of the former MP, demanded answers from the government on the cause of the helicopter crash that also claimed five other people.
Mr Gachagua, the Democracy for Citizens Party (DCP) leader, said the Directorate of Criminal Investigations (DCI) and the Kenya Civil Aviation Authority (KCAA) could not be expected to conduct an independent investigation into the incident.
Speaking on Friday at the home of the former MP in Mogondo village, Emurua Dikirr Constituency, Narok County, Mr Gachagua reiterated that senior security chiefs in the country could not be expected to oversee an independent probe into the cause of the crash.
In the February 28 helicopter crash in Chepkiep village, Mosop Constituency, Nandi County, those who died were MP Johana Ng'eno, George Were (pilot), Nick Kosgei (photojournalist), Amos Kipngetich Rotich (an officer with the Kenya Forest Service), Carlos Robert Kibet Keter (a teacher) and Wycliff Kiprotich Rono (a protocol officer at Narok County Government).
"We cannot trust the Kenyan police and other departments with this matter," Mr Gachagua said, asking President William Ruto to invite the British and American investigators.
Mr Gachagua said several issues had been raised in relation to the helicopter crash, but no answers were forthcoming from relevant government investigating agencies.
He claimed that the helicopter was flown from Endebess in Trans Nzoia to Eldoret International Airport for refuelling, but was briefly impounded before phone calls were made by senior government officials, leading to its release.
The DCP leader also questioned the quality of fuel used and claimed some airport officials had been sacked as part of a cover-up. However, he did not share proof of his allegations.
'No information, no progress'
Gachagua promises to build mausoleum for late MP Johana Ng'eno
The family also said it had not received any information on the progress of the investigations into the helicopter crash and was following developments from third parties and social media.
"No one has come here to inform us of the progress made with the investigation into the death of my son, Johana Ng'eno. Those in government have not returned since my son was buried, and we are completely in the dark," Ms Temas said, in the company of family members.
Speaking on Thursday while announcing that she was ready to welcome Mr Gachagua and his team, Ms Temas said she felt abandoned by the government, with promises made regarding their welfare not having been fulfilled.
"I understand there are attempts to cover up the issues relating to the helicopter crash that killed Johana and the others. But I want to assure those involved that the truth will come out in the end," Ms Temas said.
The government had promised it would release the findings of the investigation into the crash within the shortest time possible, but a progress report has not been issued to date, fuelling speculation that the helicopter might have been sabotaged.
Mr Gachagua visited the former MP's home five months after he was buried to pay his respects, as he could not attend the funeral owing to the tension at the time.
Without the anticipated drama, Mr Gachagua, accompanied by Nyandarua Senator John Methu and DCP's parliamentary candidate in the May 14 by-election, David Kibet Rotich, drove into the home at Mogondo village on Friday mid-morning.
It comes against a backdrop of threats of violence against him and his supporters, with Emurua Dikirr MP David Keter and Narok Deputy Governor Tamalinye Koech saying Mr Gachagua should keep off the area.
Widow skips Gachagua event
President William Ruto with Naiyanoi Ntutu, the wife of late Emurua Dikirr MP Johana Ng’eno, and her daughter Taparon Cheruto.
Photo credit: PCS
Mr Gachagua laid a wreath of flowers at Ng'eno's graveside after being welcomed by the former MP's mother, Mary Temas, and other family members, with the widow, Nayainoi Ntutu, conspicuously missing.
Ms Nayainoi's absence is believed to have been a result of her holding a government position as a director at the Information Communication Technology Authority, and being a member of the ruling UDA party.
"I have come here today to pay my respects to Johana Ng'eno, who was my great friend. I came to condole with the family, especially the mother, Mary, who has been through a lot since then," Mr Gachagua said.
He added: "Since the burial on March 6, no one in government has returned to check on her welfare, yet they knew the late Ng'eno was taking care of her in her old age. They made a lot of promises during the funeral, but they have abandoned her."
He claimed that one of Mama Temas's children, the former MP's brother, had been detained at a hospital in Eldoret, Uasin Gishu County, with a pending bill.
Mr Gachagua said: "I will take care of issues relating to electricity bills, medication, food and a driver to take her around. It will be my responsibility. As a friend of the late MP, I will take care of her as anyone would take care of his mother."
Ms Temas had earlier stated that her family was ready to welcome Mr Gachagua, whom she said was a personal friend of her departed son, and the leaders in his entourage into the homestead.
"I have heard that some people are out to block Mr Gachagua and his team from accessing our home. What is the motivation for them to want him out of the constituency? What is it they are afraid of?" Ms Temas wondered.
"My home is open to all, and Gachagua is free to visit us just like other leaders and ordinary Kenyans, be they from the local community, other communities, from Kenya or even other countries. The other day, we welcomed people from Uganda and Tanzania who were friends and followers of the late Johana. I do not understand why people want to block my visitors," she said.
