The 47-year-old, who cannot be named, was put on trial in the ACT Supreme Court last week.

He was accused of molesting the girl repeatedly after marrying her mother, including while he gave the stepdaughter a piggy-back and while at their southside home.

Some of the crimes were alleged to have occurred when the girl came to his bed after having bad dreams.

The girl claimed to have told her grandmother of the acts, but said she urged her grandmother not to tell anyone.

The girl said she then complained about the alleged abuse again when her mother and the defendant split in 2003, and went to police in 2006.

But defence barrister Steven Whybrow warned the jury from the outset that the timing of the complaint to police would cause them some scepticism.

Mr Whybrow said last week that the woman went to police in the middle of a court custody battle between his client and the complainant's mother, in which both had just sworn affidavits.

In the background to the allegations, he said, there were disputes about property and child custody, as well as changes in family dynamics.

The jury was sent out to deliberate on Thursday, and returned verdicts of not guilty on all counts.

The trial took place before Justice Richard Refshauge.

Correction: An earlier version of this story incorrectly stated that the complainant"s grandmother had urged her not to tell anyone about the alleged abuse. This was an error. The complainant had urged her grandmother not to tell anyone about the abuse.