Book: Ghost Burgler
Here is a link to a website promoting a 2012 book titled "Ghost Burgler" about a high profile burglar named Bernard Welch who was active in the 1970's and 80's.
One of the authors was a member of the Montgomery County Police force in the 1970's, and as such would have been involved in the Lyon case, and in burglary cases involving Lloyd Welch. Note that after retiring from MCP, Mr. King worked for Security in Montgomery County schools, using his experience to protect children.
Bernard Welch (subject of the book) escaped from prison in September of 1974 and made his living burglarizing homes for high value items. Many of these homes were in Montgomery County.
In 1980, Bernard Welch murdered Dr. Michael Halberstam of Great Falls, Virginia while in the process of burglarizing the Halberstam home.
He was captured, tried and convicted of that murder and sent to a Chicago prison, from which he escaped in 1985.
I do not know if there is any relation between Bernard Welch and Lloyd Welch. They were of simialr criminal professions, but a world apart in regard to organization and "success". Both have spent time in prisons where they belong.
One of the book's authors, James D. King was one of the chief investigators of the Ghost Burglar cases for the Montgomery County Police Department in Maryland. From his work on various robberies, King developed an interest in antiques and art theft. After extensive research, he wrote several articles for the International Archive of Art and Antique Theft.
This research, combined with his work on the Welch case, led him to write and champion a Montgomery County law that required sellers of precious metals and antiques to produce identification and the buyers to report the purchases to the police. This law became the model on which a Maryland state law was based, on behalf of which King was called on to testify.
LINK:
http://www.ghostburglar.com/p/about-authors.html