Taylor Swift ends her trial in tears as lawyer insists photo proves no assault took place.

Jurors have begun deliberating in the trial of duelling lawsuits between pop star Taylor Swift and a Colorado DJ she accuses of groping her while they posed for a photo together during a pre-concert fan reception.

In closing arguments on Monday, Swift’s attorney Douglas Baldridge questioned former DJ David Mueller’s credibility.

In duelling lawsuits, Swift said Mueller groped her at a backstage 2013 event and Mueller accused Swift, her mother and a Swift representative of getting him fired while denying the groping accusation.

Baldridge noted Mueller lost audio recordings he took secretly during a meeting with his bosses after he was fired from a Denver country music station.

He said that "no credibility goes with a story-changing, evidence-destroying aggressor like David Mueller".

Mueller's lawyer told jurors that the pop star's account is inconsistent with the testimony of every other member of her team. As the pop star cried in federal court during closing arguments, he questioned why Swift was smiling in a photo taken at the time she said the alleged assault took place.

"Look at Ms. Swift's face. Is that the face of someone who's in shock, who is upset?" Gabriel McFarland, representing Mueller, said while showing the photograph from before a 2013 concert with Mueller and Swift together that Swift has said was taken the moment he grabbed her backside.

The eight-member jury must rule unanimously on Mueller's claim that Andrea Swift and Frank Bell wrongly caused Mueller's firing. A judge removed Swift as a defendant in the firing claim.

The jury also must reach a verdict on Swift's counterclaim of assault and battery and her request for a symbolic $US1 judgment.

Listen: Taylor Swift's response to alleged sexual harassment gives us hope.