She said there were changes in the patterns of all three parties' accounts from December 2006 onwards.
In 2006, Ms Yusuf's account saw about 50 transactions per month - automatic payments, eftpos debits and ATM withdrawals.
Documents placed before the jury showed trips to Burger King, The Warehouse and superettes.
In February and March 2007 - when she was dead, according to the Crown - there were no such eftpos debits, only cash ATM withdrawals.
Unlike the sums Ms Yusuf had previously taken out, they were sometimes upwards of $500.
Ms Little also reviewed Reddy's Kiwibank account over the same period.
In 2006 there appeared to be regular transactions, sometimes numbering more than 40 a month.
By the middle of 2007, at times there were fewer than 10.
Detective David Sanday earlier gave evidence of statements that Reddy had made to police in 2013.
He said Reddy told him he and Ms Yusuf used each other's bank accounts and knew the pin numbers to one another's eftpos cards.
The court also heard how the defendant allegedly told police the last time he had seen his partner was when she was getting a taxi to the airport to meet an aunt who was arriving from Australia.
The defendant believed they had then gone to Hamilton.
Reddy claimed everything was "normal" in the relationship at the time.
"There were no arguments and everything was good. I think she was happy because her ex-husband did not know where she was," Reddy said, according to Mr Sanday.
Ms Yusuf was living in Howick at the time of her disappearance and the defendant allegedly told police he would only stay the night at weekends.
"She told me if I got caught living at the house, WINZ would withdraw her benefit."
Between April and October 2014, police launched an extensive undercover operation targeting Reddy.
The court will hear through the trial how an undercover officer gained the defendant's trust through a series of "simulated criminal scenarios".
Eventually Reddy made admissions that he had killed the victims and buried their bodies, before unwittingly leading officers to the burial site.
But defence lawyer Jonathan Krebs warned the jury to be critical of the so-called confession.
"I say to you from the outset: it's false, it's a cobbled-together story."
He said his client was effectively groomed by undercover officers to the point where there was "immense pressure" on the 42-year-old to make admissions.
"What if a person didn't commit the crime but knew enough about the crime to give a plausible narrative?" he said.
The trial continues.
