PHOENIX -- Rep. Gabrielle Giffords returned to Houston on Sunday after spending the weekend with her family in Tucson.

The visit was the Arizona Democrat's first trip home since was shot in the head at a January political event. Six people were killed in the attack and 12 others besides the congresswoman were wounded.

Giffords boarded a private plane late Sunday morning after spending nearly two days in Tucson, Giffords Chief of Staff Pia Carusone told The Arizona Republic. Details of the visit by Giffords and astronaut husband Mark Kelly were being kept private at his request.

Kelly announced the visit in a news release Friday, and the couple and one of Kelly's daughters arrived in Tucson that evening.

"We've been dreaming of this trip for some time," Kelly said in a statement. "Gabby misses Tucson very much and her doctors have said that returning to her hometown could play an important role in her recovery."

Carusone and Giffords spokesman C.J. Karamargin did not immediately respond to calls from The Associated Press on Sunday.

Giffords was released from a Houston hospital Wednesday and is set to start outpatient therapy. She had been in the rehab facility since late January, a few weeks after the shooting.

Giffords is now living in Kelly's home in League City, a town 26 miles (42 kilometers) south of Houston. She will continue outpatient therapy at TIRR Memorial Hermann, the same hospital where she underwent rehabilitation.

Giffords has been struggling to relearn how to speak and walk, and will be assisted by a 24-hour home health provider, according to a statement from the hospital.

Her alleged assailant, Jared Loughner, has pleaded not guilty to 49 charges stemming from the Jan. 8 shooting. He has been at a Missouri prison facility since a judge declared him mentally incompetent to stand trial May 28. Mental health experts will try to make him psychologically fit.