By Katelyn Polantz, Jeremy Herb and Marshall Cohen, CNN

(CNN) -- Adding to their portrait of Paul Manafort's wealth, prosecutors on Thursday walked jurors through the hundreds of thousands of dollars the former Trump campaign chairman spent on a karaoke machine, landscaping, home improvement and what a landscaper described as one of the biggest ponds in the Hamptons.

Special counsel Robert Mueller's team has made Manafort's expensive tastes -- from a $15,000 ostrich jacket to a $10,000 karaoke machine and a flower bed in the shape of an "M" -- a key part of their case against the former Trump campaign chairman, arguing that his expensive habits illustrate why they say Manafort broke tax and banking laws.

Mueller's team is also planning Thursday to move into the nuts and bolts of its case against Manafort, who is charged with 18 counts of tax and banking crimes.

Prosecutors intend to use the testimony from Manafort's business and personal estate bookkeeper, Heather Washkuhn, to underline Manafort's alleged criminal use of unreported foreign bank accounts. In her testimony, Washkuhn denied knowing about the companies Manafort used to wire money for his extravagant personal purchases.

Manafort has pleaded not guilty to all charges, and the trial is clearly on the mind of his former boss, President Donald Trump, who tweeted several times about the case on Wednesday. While Manafort's case isn't about the 2016 campaign, he's the first defendant Mueller's team has taken to trial, and the outcome could affect public opinion of the special counsel investigation the President has called a "witch hunt."

Gates likely will testify. What about Manafort?

On Wednesday, prosecutors opened the door to the idea they might not call Manafort's former deputy, Rick Gates, to testify, but Thursday they said Gates could be called as early as Friday or Monday.

Gates is seen as a star witness for the prosecution, and Manafort's defense team has signaled it plans to make Gates a key part of its defense, arguing that Manafort was misled by his longtime deputy.

Another lingering question -- will Manafort himself testify? -- was addressed by Judge T.S. Ellis on Thursday during a discussion about whether Manafort's team could discuss the fact that Manafort was not subject to an IRS audit.

Ellis said he did not yet know if Manafort would testify in his own defense, and didn't want to force a decision from the defense team until they begin their side of the case after the prosecution's case rests, likely next week.

"He will not be penalized for the right to remain silent," Ellis said.

However, Ellis added that if Manafort does testify, the judge may allow testimony about whether Manafort tried to comply with IRS policy and offered to be audited before he was charged.

A (big) pond in the Hamptons

The parade of expensive purchases continued Thursday, as landscaper Michael Regolizio testified about how Manafort -- and Manafort alone -- commissioned him to care for hundreds of flowers at his house as well as "one of the biggest ponds in the Hamptons."

He said Manafort paid for much of the work through international wire transfer and was his only client to do so.

Regolizio testified that Manafort spent about $450,000 on landscaping over five years. At first, the landscapers handled only tree-care for Manafort's estate. But in 2012, they took over the entire home's outdoor work, sending landscapers there four-to-five times a week to prune 14-foot hedges, mow the lawn and fertilize, plant "hundreds and hundreds of flowers," prune a flower bed next to the tennis courts, maintain the large pond with a waterfall feature and care for a white and red flower bed in the shape of an "M."

Prosecutors read details about wire transfers that Manafort sent to pay for a karaoke system in 2010 during the parade of testimony from vendors who sold high-end goods and services to Manafort. The vendors said they were all paid via international wire transfers coming from offshore shell company accounts.

In addition to the karaoke set, which came from the whole-house audio-video design company Sensoryphile, Joel Maxwell of Big Picture Solutions told the jury that Manafort installed Apple TVs, networks and other electronics in his Hamptons home from 2011 to 2014 at a cost of $2.2 million.

A pattern has emerged in many of the witness' testimonies at Manafort's trial this week. Vendors who sold custom men's clothing, audio-visual services, landscaping, home renovations and cars have told the jury that Manafort was a major customer and frequently paid with the unusual method of wiring money from corporate-named bank accounts in Cyprus.

The vendors largely say they do not recognize the company names Manafort used, yet they knew the payments came from him because their amounts matched the bills they sent him.

Fake invoices

Regolizio said he never met, communicated with or received payments from Gates, Manafort's longtime deputy on whom defense attorneys have indicated they'd like to pin the alleged crimes.

Prosecutors also revealed yet another document that showed a bill from Regolizio's company, New Leaf, but with an incorrect vendor name and address.

Defense attorney Jay Nanavati asked him if Regolizio would call the document a "fake invoice." Regolizio replied yes.

Immediately after they showed the jury the invoice, prosecutors asked Regolizio if he had ever met or corresponded with Konstantin Kilimnik, a Russian who has been indicted in DC in a separate case for helping Manafort attempt to tamper with witnesses.

Regolizio said he did not know Kilimnik.

Prosecutors have not yet revealed what they believe the fake invoices prove in their case.

Manafort's bookkeeper testifies

For a nearly silent few minutes in the courtroom Thursday, Washkuhn denied knowing about the companies Manafort used to wire money from overseas. Prosecutor Greg Andres asked Washkuhn if she had ever heard of 14 different shell-company bank accounts.

She said "no" to every one.

Washkuhn never recorded the existence of any foreign bank accounts for Manafort while she kept his books, she said.

In addition to Manafort's alleged criminal use of unreported foreign bank accounts, prosecutors say she will also be able to speak to his alleged criminal bank fraud charges.

Washkuhn said she handled all of Manafort's personal and professional financial dealings from 2011 to 2018, and it was important for her to keep track of all of his bank accounts and bills so she could help him properly pay his taxes each year.

"He approved every penny of everything we paid," Washkuhn testified.

She also said she hadn't known if he had accounts in Cyprus, St. Vincent, Grenadines and Ukraine. Many of the personal items Manafort bought were paid for by international wire transfers from banks in Cyprus, the witnesses before her testified.

In addition, she said she had no knowledge of at least one loan his political consulting company DMP International made to one of the shell companies for $275,000.

Arguing over ostrich jackets

Over the first two days of the trial, Mueller's team and Ellis have clashed over whether prosecutors can show photos of Manafort's purchases, such as his $15,000 ostrich jacket. Ellis has reminded the lawyers and jurors that it's not a crime for a person to be rich.

In a court filing, Mueller team's formally argued they should be allowed to show proof of Manafort's extravagant lifestyle, including photos of his high-end custom jacket, his real estate expenditures and other extravagant purchases.

Prosecutors say evidence of what Manafort spent his Ukrainian lobbying proceeds on is evidence of the crime itself, and shows how he personally benefited from allegedly defrauding the government.

"That Manafort had an expensive lifestyle that required lots of money to maintain is important proof as to why he would commit the bank frauds" after his lobbying work declined in 2014, prosecutors wrote.