Chinese state media announced last week that Bo's wife, Gu Kailai, and a family employee were in custody on suspicion of murdering the Briton, who died in Chongqing last November.
Bo, then party secretary of the south-western city, has been suspended from key political roles and is under investigation for disciplinary violations.
Journalist Chu Chaoxin wrote on his microblog: "I don't deny that I posted the name of Neil Heywood first in March. Because of this, yesterday there were public people [presumably police] without licences who were trying to find me and harassed my friend and intended to take him to the police station with the excuse that he didn't have a temporary residency certificate [for the city]."
He added: "After negotiation and airing it on the microblog, police apologised. The truth proved that Neil Heywood is not a rumour. If they want to lock up people who told the truth, I am willing to be that person and make history."
The claims that Gu had killed Heywood first surfaced in a series of microblog posts in March, citing a mystery text message received by the journalist.
Chu could not be reached for comment, but people with knowledge of the incident said the message – from an unknown number – said only that Heywood had been killed and did not give further details or mention either Bo or Gu. They said Chu's post about the death was deleted and it is not clear how the allegations about Gu's involvement surfaced weeks later.
The UK first announced that it had asked China to reinvestigate the case in March. Bo's former ally and police chief, Wang Lijun, is believed to have told US officials of his suspicions about the death when he fled to the US consulate in Chengdu in February. He is now under investigation by Chinese authorities.
Prior to news of Gu's detention, Heywood's family said that the 41-year-old died of a heart attack.
British consular officials in China expressed suspicion about the death but no action was taken because other officials thought asking Chinese authorities to investigate would be problematic, the Wall Street Journal reported.
It cited unspecified sources who added that some British officials knew local police had pressured Heywood's Chinese wife to agree to a swift cremation without an autopsy. Police have warned Lulu Wang not to speak to foreign media, Reuters reported .
Chinese state media has sought to play down the scandal, which comes months before power is transferred to a new generation of leaders. A commentary in the Global Times argued: "Bo's case is an independent incident of a violation of party discipline and China's laws. What's going on is the inevitable result of a lawful investigation. It is an exaggeration to say the case mirrors China's 'political fight'."
