The deliberations on Thursday come after three weeks of trial in Waterbury, Connecticut, not far from where a gunman killed 20 small children and six staff members at Sandy Hook Elementary School in December 2012.

Jones claimed for years that the massacre was staged by the government as part of a plot to take away Americans' guns.

In closing arguments earlier, lawyers for the families of eight Sandy Hook victims said Jones and his company, Free Speech Systems LLC, cashed in for years on lies about the shooting, which drove traffic to his Infowars website and sales of products there.

The families, meanwhile, suffered a decade-long campaign of harassment and death threats by Jones' followers, lawyer Chris Mattei said.

"Every single one of these families were drowning in grief, and Alex Jones put his foot right on top of them," plaintiffs' lawyer Chris Mattei told jurors.

Jones' lawyer, Norman Pattis, countered during his closing argument that the plaintiffs had shown scant evidence of quantifiable losses. Pattis urged jurors to ignore the political undercurrents in the case.

"This is not a case about politics, I remind you that," he said.

"It's about how much to compensate the plaintiffs."

The trial was marked by weeks of anguished testimony from the families, who filled the gallery each day and took turns recounting how Jones' lies about Sandy Hook compounded their grief.

An FBI agent who responded to the shooting is also a plaintiff in the case.

Jones, who has since acknowledged the shooting occurred, also testified and briefly threw the trial into chaos as he railed against his "liberal" critics and refused to apologise to the families.

In August, another jury found Jones and his company must pay $US49.3 million ($A76.7 million) to Sandy Hook parents in a similar case in Austin, Texas, where Infowars is based.

Jones' lawyers hope to void most of the payout before it is approved by a judge, calling it excessive under Texas law.

Australian Associated Press