As investigators searched Andersons truck they discovered several receipts for duct tape, black water-based Tempura paint, paintbrushes and a bucket, most of which was purchased a few days prior to and on the day Piper went missing. Investigators suspected that the paint was used to disguise Andersons Bronco. Their suspicions would prove to be correct.
They called in experts to analyze the paint job on the truck more closely. Samples were taken and chemically tested. They found that the Bronco had been painted with the same material bought by Anderson around July 29th. The paint used was a kind that could be easily applied and washed off.
Interestingly, a witness claimed that he saw Anderson cleaning his car on the same day Piper disappeared. It was believed he was washing off the paint and ridding the car of any other incriminating evidence. Yet, he failed to do a thorough job.
Inside the Bronco, investigators found even more incriminating evidence. They discovered a wooden platform that had holes drilled into it. It was believed that it was made as a restraining device in which a persons ankles and hands could be tied to metal hoops that were strategically inserted into the board. The platform had been sized to fit perfectly into the back of the truck.
The investigative team also found hairs attached to the wooden platform, which genetically matched Pipers. Moreover, a dirty shovel, furniture moving straps, weeds, a toolbox and dog hairs similar to those of the Streyles dog were also discovered in his truck. It was becoming increasingly clear that Anderson had a darker side than that which he presented at the police station.
At Andersons Sioux Falls home, investigators found a pair of jeans in his laundry basket. They were stained with what appeared to be blood. The jeans were taken to a police lab and analyzed. They found that the DNA structure of the blood did not match that of Anderson or his family. It was believed to have been Pipers blood. They also found semen stains on the jeans but they were not able to genetically match them to Anderson because they had such a limited specimen to test.
During the search, investigators also discovered a set of handcuff keys at his home. However, Anderson vehemently denied that he owned a pair of handcuffs. After questioning, Anderson was free to leave. Yet, the police had little doubt that he was involved in Pipers kidnapping. They just needed more proof to make their case.
On the same day of Andersons interview, Shaina and Vance were called into the police station to view a six-picture photographic line-up. One of the pictures was an outdated drivers license photo of Anderson with long hair and a mustache. Shaina and Vance were unable to identify the man that had come to their house.
Approximately two days later, Shaina and Vance were asked to return to the police station to view some more photos. Once again, Andersons picture was included in the photographic line-up. This time they had a more current photo depicting him with shorter hair and cleaner shaven. Almost immediately Vance picked out the picture of Anderson as the man who had come to the house on July 26th. Shaina separately picked out the same photo and identified him as the man who took her mother.
The positive identification gave Sioux Falls police the evidence they needed to press charges against Anderson. On August 2, 1996 he was arrested on two counts of kidnapping. They were unable to charge Anderson with murder because they lacked evidence of a body.
In September of that year, the police launched a massive search for Piper and any other evidence that might convict Anderson of murder. They wanted to make sure he would be jailed for the full extent of his crime. They employed the help of hundreds of volunteers who searched the wooded area around the Big Sioux River, close to the town of Baltic, South Dakota.
During the hunt for evidence, several significant items were discovered. Half of a shirt shorn down the middle with the logo Code Zero was found. It was the same shirt Piper was wearing on the day she disappeared. A man picked up the other half of the black and white striped shirt on July 29th on a road near Baltic. According to court documents, he initially thought it was a referee shirt, yet when he discovered it wasnt he threw it in the back of his car and forgot about it. He later gave it to the police when he realized the shirts significance.
Near the Big Sioux River where part of the shirt was found was a roll of duct tape with human hairs attached to it. The hair was later analyzed and found to be consistent with samples taken from Pipers hairbrush. Moreover, the duct tape taken from the scene matched the roll recovered from Andersons truck two months earlier.
More gruesome physical evidence was discovered around the river, which included several lengths of rope and chains, eyebolts, a vibrator and a half burned candle. It was believed that the items were used to torture Piper. They also presented clear evidence that Anderson was a sexual sadist.
In May 1997, Anderson was tried and found guilty of kidnapping Piper. He was eventually sentenced to life imprisonment in South Dakota State Penitentiary. However, it would not be the only charge for which he would be convicted.