What was the status of Dred Scott while he was living in the territory of Wisconsin?

Immigrant/Slave was his status.

Dred Scott v. Sanford, 60 US 393 (1857)

There is some dispute as to whether Dred Scott lived with Dr.

Emerson in the Wisconsin Territories or Upper Louisiana Territory (the Supreme Court documentation refers to the Upper Louisiana Territory, but most historical accounts refer to the Wisconsin Territories); however, his status in either area would have been that of a free man.

In the Wisconsin Territories, slavery was prohibited by the Northwest Ordinance (aka "An Ordinance for the Government of the Territory of the United States, North-West of the River Ohio," affirmed by Congress in 1789); in Upper Louisiana Territory, he would have been free by virtue of living north of the 36th parallel, per the Missouri Compromise of 1820.

Dred Scott would also have been free when stationed with Dr.

Emerson at Rock Island, Illinois, because of Illinois' status as a "free state."

The accepted doctrine prior to the Supreme Court ruling in Scott v. Sanford, (1857), was "once free, always free."