I'm not certain that CB acted alone.
Here's an excerpt of an interview with KR, who said he knew CB in the months before Madeleine vanished because they both parked their camper vans at Barranco beach. He claimed CB tried to recruit a mutual friend to steal a child:
"We were sitting around the fire one night after a meal, we had a few beers and during the early hours of the morning my friend began to cry. I asked him what the matter was and, eventually, he confessed to me he was getting involved with Christian to steal a child from Praia da Luz from a rich family."
"I said you can't get involved in kidnapping a person for ransom, that's ridiculous, then he explained - 'no, it's not like that'. Christian had a customer, a buyer lined up, a German couple who couldn't have children."
Then there's LC, CB's former prison inmate:
“He told me that in Portugal, he had stolen there. He was in an area of hotels where rich people live. And when he went to the hotel area, there was an open window somewhere, he told me. And he would have entered this window for money and gold. However, he did not find any money, but came across a child and took it with him. About two hours later, the area was full of police and dogs and he had left from there.”
"He left the area. He then said that there was another person with him who he had argued with and that they had split up."
Both accounts seem to imply that CB was acting with another person.
If so, who could he have been with, and what function did they hold?