Reuters/Phoenix

Courtroom artist’s depiction of Jared Loughner  accused of attempting to kill US Congresswoman Gabrielle Giffords of Arizona and shooting 19 others at a shopping mall in Tucson on Saturday. Loughner appeared with his attorney Judy Clarke, before US Magistrate Judge Lawrence Anderson at the Sandra Day O’Connor Courthouse in Phoenix on Monday

A troubled 22-year-old college dropout made his first court appearance on Monday on five federal charges, including the attempted assassination of US Representative Gabrielle Giffords, who remained in critical condition with a bullet wound to the head.

His hands manacled together, Jared Lee Loughner said in a strong voice he understood the charges against him involving a shooting spree in Tucson on Saturday that left six people dead and 14 others wounded.

The bloody rampage -- at an event Giffords hosted for constituents -- has fueled debate about whether heated rhetoric seen in recent US political campaigns can lead to violence.

President Barack Obama, who stressed unity after the shootings, plans to go to Arizona today to attend a memorial service for the dead, who included a federal judge, a nine-year-old girl and one of Giffords’ young aides.

Last year, Giffords had warned that angry campaign talk had prompted violent threats against her and vandalism at her office.

A police mug shot taken of Loughner after his arrest and released on Monday shows the accused killer, who faces a possible death sentence, smiling broadly.

At his court appearance, Loughner’s lawyer waived a detention hearing. Federal Magistrate Judge Lawrence Anderson ordered Loughner held, calling him a danger to the community.

The judge scheduled a Jan. 24 preliminary hearing.

Having survived a shot to the head at point-blank range, Giffords, a popular 40-year-old Democrat, remained in critical condition at a Tucson hospital.

Doctors said there was no increased swelling of her brain and she continued to respond to simple commands such as squeezing a finger and wiggling her toes.

“There have been no complications,” Dr Peter Rhee of University Medical Center in Tucson told the PBS programme Newshour. “We’re happy with where we are. But we have to give her some time to see how she’s going to do.”

A single bullet passed through her brain on the left side, hitting an area that controls speech. The extent of brain damage she may have suffered is uncertain, doctors said.

At the White House, Obama mourned the dead.

“Right now the main thing we’re doing is to offer our thoughts and prayers to those who’ve been impacted, making sure that we’re joining together and pulling together as a country,” Obama said.

In Denver, federal prosecutors charged a Colorado man on Monday with threatening gun violence and arson against staff of US Senator Michael Bennet in the days before the Tucson shootings.