Police are only calling the two "John and Jane Doe," because investigators are still trying to sort through their aliases.
Investigators the two were arrested after neighbors spotted a man and woman breaking into a home on County Line Road.
The neighbors called police, who were able to apprehend the pair.
Authorities say the alleged thieves had a pillowcase full of jewelry at the time.
Police are trying to determine if they were behind a dozen other burglaries in Radnor over the past three months.
Immigrations and Customs Enforcement agents are helping identify the suspects.
Police also say fingerprints from the two also matched those found at crime scenes in New Jersey and New York.