However, a police statement said the programme has not raised any issues that were not either implicitly or explicitly put before the court.
These inquiries are routine and are conducted whenever police receive information of this nature.
• QC hits out at Bain documentary
Police had no further comment on the programme itself or these inquiries.
The television documentary, which called into question evidence at David Bain's retrial has been slammed as "farcical" by Bain supporter Joe Karam, who says the programme's maker refused to approach the defence team for input.
Bain was convicted in 1995 of murdering his parents, Robin and Margaret, and siblings Laniet, Arawa and Stephen in their Dunedin home.
He was found not guilty in a retrial in June last year, after his defence team had argued that Robin Bain had shot the other four family members before turning the gun on himself, with the motive being his incestuous relationship with daughter Laniet.
In The Investigator Special: The Case Against Robin Bain, screened on TV One last night, documentary maker Bryan Bruce called into question some of the evidence given by defence witnesses.
The documentary singled out the testimony of the retrial defence's surprise witness Daryl Young for special attention, quoting two people who contradicted the photocopier salesman's evidence about his dealings with Robin Bain as principal of Taieri Beach School.
Bruce said Robin Bain had been in effect put on trial and vilified without the benefit of a proper legal defence.
He said there was no forensic evidence linking Robin Bain to any of the murdered family and his documentary showed the questionable chain of actions Robin would have had to have performed - including shooting himself without leaving any of his bloody fingerprints on the bloody gun.
Mr Karam said today the factual basis of the documentary was "so askew as to be farcical".
"It's just unmitigated rubbish," he told NZPA.
"About the only thing I agree with him is that the police should be called in quickly, and they should be knocking on his door for masquerading as a serious documentary maker."
It was "disgraceful" that TVNZ screened the documentary without Bruce seeking input from the defence team, Mr Karam said.
"They refused to approach us."
Bain's lawyers only learned the documentary was being made earlier this year after the court sent them copies of letters from Bruce asking for court documents, Mr Karam said.
When in May they received another letter from the court saying the documentary was almost finished, the defence team wrote to TVNZ and Bruce asking for the documentary to be postponed.
"How can you possibly do a balanced programme about the defence case without talking to the defence?"
The documentary did not follow the normal broadcasting standards of balance and fairness, Mr Karam said.
"Huge claims were made solely for the purpose, I would say, of increasing ratings and getting people to watch it."
It was too early to say whether a complaint would be laid with the Broadcasting Standards Authority.
David Bain's lawyer, Michael Reed QC, said the documentary had glossed over a lot of evidence about Robin's depression and his motive for killing the family.
"I am disgusted by the fact [Bruce] didn't spend one second in court, that he is challenging the jury and that he was disrespectful of the system and of the judge," he told the Otago Daily Times.
David Bain's legal team would today consider what action, if any, it would take.
