He said he was surprised she had been a part of any situation involving drugs and hoped the officers investigating would get to the bottom of what happened.
"Yeah, it does surprise me that she was involved in that.
"But... we don't know the whole story behind what happened - that's what police are doing.
"Nothing is going to bring Lauren back, but I hope that proper justice is served."
He last night praised the work of police. He had been in frequent contact with them about the investigation.
McGirr, a 37-year-old civil engineer, was remanded on bail to a North Canterbury address on the condition that he surrendered his passport and reported twice a week to a local police station.
Biddle Snr said a celebration of his daughter's life was held on November 18.
"It was a great occasion. We were surprised because it is off season with the horse people here in Florida and so we had only planned for about 200 people to come.
"We ended up having over 400 people that showed up for the celebration."
The family was "getting along", he said, despite a tough holiday period.
"We're just continuing to work, move forward, and not dwell on things."
Biddle, a promising American polo player, had been in New Zealand for just over a week at the time of her death.
She had planned to stay in Clifton, working and playing polo, until March this year.
Polo was all-consuming for the family, Biddle Snr said.
His daughter was a fourth-generation player.
Biddle Snr plays the game professionally in the US and Lauren Biddle's mother plays as well as working with horses in Florida.
Lauren Biddle had travelled to New Zealand from Australia — her second trip to Aotearoa — and had been playing across the ditch for about three weeks before arriving here.
She was also into show jumping and equestrian.
Her father earlier called her an "amazing rider".
The US Polo Association said her death was devastating.
"Lauren was a promising young player who will be lovingly remembered by the polo community as a passionate horsewoman, animal lover, adventurer and friend who lived life to the fullest."