The ACT branch is in the middle of the murkiest preselection battle in memory, after the territory gained a third lower house seat in the recent federal electoral boundaries redistribution.

The party's national executive appointed Maurice Blackburn special counsel Lee Taylor to investigate after flyers attacking right faction candidate Kel Watt were sent to first female members of the party, then MLAs.

That investigation overtook one announced by ACT Labor Branch Secretary Matt Byrne to determine whether the party's membership database had been accessed improperly.

The investigation found no evidence that anyone from the ACT branch gave out the list.

It also found no evidence that any of the other candidates were involved in the smear campaign, although they certainly stood to gain from it.

However the investigator noted he did not have the time or the resources to conduct a proper probe.

He also said while he was not familiar enough with NSW Police records to rule whether the documents contained in the flyers were forged, there were inconsistencies in the form and dates that made them appear so.

Mr Watt said he was disappointed the investigator was not given more time to try and find the culprit.

"Obviously there are candidates in this field that benefit from the smears. It's a pity the positive inroads I'd made and the the warm reception my policy ideas had have been derailed by the filthiest, lowest act in 120 years plus of preselection history. Absence of evidence isn't evidence of absence," Mr Watt said.

It's understood the investigator also took aim at the unusual dynamic between Mr Byrne and  Mr Watt.

It can be revealed Mr Byrne moved to expel Mr Watt from the party in June, after Mr Watt attended a fundraiser for Liberal MLA Mark Parton at the Canberra Greyhound Racing Club.

Mr Watt was a non-paying guest at the event and was invited by the club, who he'd previously worked for.

Mr Parton incorrectly tagged Mr Watt in a Facebook post thanking him for helping with the event. Mr Parton had meant to tag greyhound race caller Kel O'Rourke.

Mr Watt gave that information to the disputes tribunal but Mr Byrne said he hadn't received it.

The investigator thought it was unusual that such a serious stoush between a branch secretary and a candidate for preselection had been unresolved after two months.

The disputes tribunal told Mr Watt of the charge the same day Mr Watt announced his candidacy for preselection. The fundraiser had been more than a month earlier.

Mr Bryne said he had lodged the complaint before Mr Watt had announced his bid for preselection.

"My belief was the party needed to examine actions Kel had taken with regards to his support for the greyhound lobby and support for the Liberal party but as became clear it would potentially colour the upcoming preselection I decided to withdraw complaint," Mr Byrne said.

Mr Watt was the first within Labor to put his hand up for preselection in the new federal seat of Canberra but has been far from the last.

Charity boss John Falzon, lobbyist Simon Banks, staffer Jacob Ingram and policy analyst Alicia Payne have all expressed interest in running for the seat.

The national executive on Monday endorsed the ACT branch's timetable for federal preselections for the seats of Bean, Canberra, Fenner and the Senate.

Prospective candidates will have seven days from Wednesday to formally nominate for pre-selection, while members can vote in person on August 25, 29 and September 1 or cast their vote via post.

More than 1300 of ACT Labor's 1700 members will be eligible to vote in the preselections, after a rule change last year that scrapped the need for people to attend three meetings to cast a ballot.

Members can now vote in the preselections if they have been in the party for one year and live in the electorate they are enrolled in.

Mr Byrne said the rule change had tripled the number of members able to cast their vote in preselections.

“I’m proud to have led the push to enfranchise more members to be able to vote in preselections. I believe that a well contested preselection, that includes a big turn out from members to vote, will be the best preparation our candidates need to win the seats for Labor and provide strong representation for the ACT in a Shorten Labor government,” Mr Byrne said.