Paul is not affirming that the people who put Jesus to death and those who brought him off the tree were one and the same; he is merely stating that both parties were made up of Jewish individuals.
Remember John 19:38-40 (NASB) which tells us exactly who "brought Jesus off the tree."
38 After these things Joseph of Arimathea, being a disciple of Jesus, but a secret one for fear of the Jews, asked Pilate that he might take away the body of Jesus; and Pilate granted permission. So he came and took away His body. 39 Nicodemus, who had first come to Him by night, also came, bringing a mixture of myrrh and aloes, about a hundred pounds weight. 40 So they took the body of Jesus and bound it in linen wrappings with the spices, as is the burial custom of the Jews.
Both Joseph of Arimathea (see Mark15:43) and Nicodemus (John 3:1) were part of the council of rulers at the time. Both, of course, were Jewish men.
The context of Acts 13, then, gives us insight as to why Paul is speaking in this way, and that is to communicate the history and actions that led to this moment to his listeners, which consisted of both Jew and Gentile peoples.
Further context clues are found in Acts 13:46-48:
45 When the Jews saw the crowds, they were filled with jealousy. They began to contradict what Paul was saying and heaped abuse on him.
46 Then Paul and Barnabas answered them boldly: “We had to speak the word of God to you first. Since you reject it and do not consider yourselves worthy of eternal life, we now turn to the Gentiles. 47 For this is what the Lord has commanded us:
“‘I have made you[f] a light for the Gentiles,
that you[g] may bring salvation to the ends of the earth.’[h]”
48 When the Gentiles heard this, they were glad and honored the word of the Lord; and all who were appointed for eternal life believed.
Thus, when we consider the historical context and audience of the passage, we can come to the conclusion that Paul was not connecting anyone but the Jewish people, as a whole, as being those involved in the crucifixion and burial of Jesus Christ.