BREAKING NEWS Update at 2:08 p.m.:

Star witness Denise Cantu took the witness stand Thursday afternoon, reports KSAT 12 News reporter Dillon Collier.

Cantu told jurors that she and Uresti "would have sex in the bathroom of his law office. He was my friend and lover."

Uresti's wife, who was in court earlier this week, didn't appear to be in the courtroom during Cantu's testimony.

Original story:

The cross-examination of an IRS agent by an attorney for Democratic state Sen. Carlos Uresti was at times combative Thursday, as the defense attempted to dispute several flow charts presented by the government in its federal fraud case against the lawmaker and co-defendant Gary Cain.

Uresti and Cain face a combined 20 felony counts, ranging from money laundering to securities fraud, related to their work for FourWinds, the now-defunct fracking sand company.

Four people tied to the failed company have already pleaded guilty.

Uresti attorney Michael McCrum, who told KSAT 12 News on Thursday morning the evidence was going the way he thought it would, challenged for hours, the testimony of an IRS agent who used flow charts to show money going in and out of FourWinds accounts and later into accounts tied to Uresti.

The prosecution this week is expected to call its star witness, Denise Cantu, a former legal client of Uresti, who said she invested close to $1 million in FourWinds.

Federal records show all but about $100,000 of that investment was later lost.

Federal officials refused to say whether Cantu was at the federal courthouse Thursday.

A woman with her head wrapped in a jacket, and surrounded by deputy marshals, was rushed into the courthouse about an hour before testimony resumed Thursday morning.

Cantu, who has been in police custody since being arrested late last year on suspicion of armed robbery in Harlingen, was handed over to federal authorities, according to federal records.