A data research group says the immigration detention population total dropped in the first three months of the 2010 fiscal year.

The reduction is the result of a decline in detentions of immigrants without criminal convictions, the researchers say.

An analysis of hundreds of records by Transactional Records Access Clearinghouse shows roughly 27 percent of immigrants in detention in fiscal year 2009 had criminal records. But in October to December of last year, that proportion was 43 percent. The 2010 fiscal year began last Oct. 1.

The research group says Immigration and Customs Enforcement agrees the drop is related to fewer arrests of non-criminal immigrants. An ICE spokesman could not be immediately reached.