In 1670 Indians who arrived in Virginia by land were bound as servants until 
the age of 30 years, but a law of 1682 made them slaves for life. Thus, the 
court records of Henrico County differentiate between Indians "who came in 
amongst the English before the last act of assembly" (1682) and those that 
arrived after. I have a file on my site in which I quote the colonial county 
court records for most mentions of Indians:
http://www.freeafricanamericans.com/free_Indians.htm

Sometime around the Revolution, Virginia acknowledged that enslaving Indians 
had been illegal, and they freed many slaves who could prove they were 
descendants of Indian women. This process continued until about 1810 or 1820 
when testimony about what had occurred in the early 1700s was no longer 
accepted. From their descriptions in the registers of free Negroes, it is 
obvious that the Indian slaves blended with the African slaves:

"Daniel Coleman (born about 1752) registered in Petersburg on 10 February 
1798, a dark Brown free Negro or Indian, six feet two inches high, about 
forty six years old, short bushy hair, a little grey, formerly held as a 
slave by Joseph Hardaway but obtained his freedom by a judgment of the Gen'l 
Court in Nov. 1797" [Petersburg Register of Free Negroes 1794-1819, no.170].

Carolyn Goudie researched this subject while at the LVA, but I do not know 
if she published her research. You can read the family history of some of 
the Indian families who gained their freedom (Coleman, Findley, Jumper, 
Vena/ Venie) on my site: http://www.freeafricanamericans.com/Virginia_NC.htm
Paul