Wichita ? BTK serial killer Dennis Rader strangled dogs and cats before he began killing people, and began exercising to build up strength in his hands when he found it harder to choke his victims, officers testified Wednesday.

At the hearing to determine Rader’s punishment for the 10 murders that haunted Wichita over three decades, Wichita Police Department Detective Clint Snyder testified Rader told investigators it was extremely difficult to strangle people because his hands would become numb. In confessing to police, Rader showed how he used a squeeze ball to strengthen his grip.

Kansas Bureau of Investigation special agent Larry Thomas testified that after Rader killed Josephine Otero’s parents and brother in their home, he took the 11-year-old girl to the basement where he hanged her from a sewer pipe – a death Rader referred to as his “encore.”

“I remember problems with Josephine because her hair was in the way,” Rader told investigators.

Rader looked away briefly Wednesday as crime scene photos were projected on the courtroom screen. But he otherwise appeared calm throughout the hearing, sipping water or occasionally taking notes on a legal pad.

The hearing is expected to extend into today, and feature statements from victims’ relatives before Judge Gregory Waller decides whether Rader will serve his 10 sentences consecutively or concurrently.

Members of the Otero family listen to testimony in the first day of the sentencing phase in the trial of confessed BTK serial killer Dennis Rader in Wichita, as officials described the murders of four of their family members in 1974. Rader pleaded guilty this summer to 10 Wichita-area murders over a 30-year span.

Prosecutors want Rader to get the longest possible sentence: a minimum of 175 years without a chance of parole. Kansas had no death penalty at the time the killings were committed.

Wednesday’s details were wrenching for the surviving Otero children, who found their parents dead when they came home from school in January 1974. They would learn later that their brother and sister were also dead.

Carmen Otero clutched an afghan in the courtroom and nervously tapped her foot on the floor through much of the testimony. She was just 13 when she used a fingernail clipper to try to cut the gag off her mother’s face.

The two brothers, Charlie and Danny, mostly crossed their arms through the testimony, occasionally wiping away a tear. But when prosecutors projected a close-up photo of Josephine on the screen, Charlie Otero became visibly flushed, buried his face on his lap and cried.

Prosecutors also displayed on the screen Rader’s recollection of the exchange he had with Josephine before killing her.

“What’s going to happen to me?” she asks.

Rader: “Well, honey, you’re going to be in heaven with the rest of your family.”

Rader then hanged the girl and masturbated over her body.

Rader looked on as KBI special agent Raymond Lundin said the killer told authorities in an interview after his Feb. 25 arrest that he targeted Josephine because he was attracted to Hispanics.

“He said that he has always been attracted to Hispanic looking people – dark eyes, dark hair, dark skin. He said Josey was the one who caught his eye and she was his target,” Lundin said, noting that Rader also told him he was attracted to “younger women.”

“I don’t know how you call an 11-year-old a younger woman,” Lundin said.

Rader, a 60-year-old former church congregation president and Boy Scout leader, pleaded guilty in June to the slayings of the Oteros and six other people between 1974 and 1991. The murders terrorized the Wichita area until Rader was arrested in February.

While testifying about the 1974 stabbing and strangling of Kathryn Bright, Wichita police Detective Clint Snyder recalled that Rader said he did not plan on being caught and was outsmarted by police.

In describing Bright’s killing to police, Rader said, “I’m sorry. I know this is a human being, but I’m a monster.”

Rader’s long fascination with bondage was shown to the court in a photo he apparently took of himself wearing pantyhose and a bra and hanging from a pipe in the basement of his mother’s home.

When testifying about the 1977 murder of Shirley Relford Vian, Wichita Police Department Detective Dana Gouge testified Rader told investigators he intended to kill her three young children whom he had locked in the bathroom.

But he got spooked because the phone rang and the family had been expecting a visitor. The children escaped and ran to a neighbor.

Steven Relford, his arms crossed, stared with obvious disgust at Rader throughout much of the testimony about the day his mother was killed.

Steven was just 6 when Rader – in a ruse to find out where the boy lived – pretended he was a detective and showed the boy a photo of his own wife and son, asking the boy if he knew where they lived. He then watched as the boy went back to his own house.