- May 2 – Fairfax County Police Officer Amanda R. Perry is charged with reckless driving in connection with the February 12 crash that killed 33-year-old Ashley McIntosh in Alexandria.
- May 2 – 27-year-old MS-13 member Brian O. Sanchez Maradiaga is sentenced to two life terms in prison for robbing and beating 22-year-old Fredy Reyes-Castillo to death in Brown's Chapel Park in Reston on June 17, 2001.
- May 5 – The Fairfax County Board of Supervisors approves the Clark Construction Group's proposal to build a new 46,000 square foot library and a senior and workforce housing development, Lee Village at Silver Lake, on a 6.64-acre parcel of county-owned land at the intersection of Silver Lake Boulevard and Beulah Street in Alexandria.
- May 6 – A magnitude 1.8 earthquake occurs in Annandale.
- May 10 – 49-year-old Michael A. Ross is shot to death in an apartment in the Penn Daw neighborhood of Alexandria.
- May 16 – Judge Stanley P. Klein sentences 23-year-old Ahmed I. Osman to 73 years in prison for the robbery and murder of 46-year-old cab driver Parvez Ahmed in Falls Church on June 11, 2006.
- May 19 – The Fairfax County Board of Supervisors confirms the Park Authority Board's selection of John W. Dargle, Jr. as director of the Authority.
- May 23 – Alfredo R. Prieto is given two death sentences by Judge Randy I. Bellows for the murders of Warren H. Fulton, III and Rachael A. Raver in Reston on December 4, 1988.
- Fairfax County Police Department. Public Information Office. UPDATE – Officer Charged in Fatal Crash. Fairfax County Police Department News Releases. Fairfax County Police Department, 2 May 2008. Web. 12 Feb. 2012.
- Jackman, Tom. "VIRGINIA BRIEFING: Two Life Terms in Gang Slaying." Washington Post. The Washington Post, 03 May 2008. Web. 04 Sept. 2014.
- Meer, Claudia. "Mixed-Use Development at Kingstowne Regional Library Site Will Accelerate Library Construction." Kingstonian Mar. 2008: 24-25. Print.
- Horrock, Nicholas M. "New Lee Library Approved." Springfield Connection 15 May 2008: 3. Print.
- Jackman, Tom "The Earth Moves. Annandale Yawns." The Washington Post: B.1. National Newspapers Core. May 07 2008. Web. 8 Jan. 2012
- "Homicide in Penn Daw." Alexandria Times. Alexandria Times, 13 May 2008. Web. 4 July 2016.
- Jackman, Tom. "VIRGINIA BRIEFING: Fairfax County." The Washington PostMay 17 2008. ProQuest. Web. 18 Aug. 2016.
- Moore, Ken. "Greed, Murder and Grief: Killer of Alexandria Cab Driver Sentenced to 73 Years in Prison." Alexandria Gazette Packet 22 May 2008: 1+. Print.
- "Courier." Briefs: Dargle Named Park Authority Director 40.12 (6 June 2008): 7.
- Jackman, Tom. "Two Death Sentences In '88 Fairfax Killings." Washington Post. The Washington Post, 24 May 2008. Web. 13 Sept. 2014.
|Fairfax County by Year: 2008|
|April 2008||·||May||·||June 2008|