- December 3 – Fairfax County Sheriff Carl R. Peed fires Deputy Jabar Shabazz for violating department rules against making public statements.
- December 7 – Following the retirement of Chief Glenn A. Gaines, Edward L. Stinnette becomes the acting chief of the Fairfax County Fire and Rescue Department.
- December 9 – 35-year-old teacher's aide Marybeth Geddes is struck and killed by a hit and run driver as she attempts to cross Leesburg Pike near Pimmit Drive in Falls Church.
- December 10 – 40-year-old Fairfax County Police officer Larry H. Jones is convicted of illegally discharging a firearm in public in Loudoun County General District Court. Officer Jones had shot a cocker spaniel in the yard of his house in Sterling, on September 22, claiming he feared that the 30-pound dog was about to attack him.
- December 19 – 81-year-old Lorraine P. Ayres is killed when she turns her 1996 Cadillac DeVille into the path of a 1994 Ford Econoline Van on Little River Turnpike in Alexandria.
- December 20 – 32-year-old Elaine S. Rowland unintentionally kills herself in an early morning crash in Centreville when she loses control of her speeding 1996 Ford Escort and is partially ejected when the car rolls.
- December 22 – 42-year-old Gloria Prudencio stabs and beats her daughter, 18-year-old Yiti C. Arevalo, then sets her on fire in the family condominium at 3100 Manchester Street South in the Woodlake Towers Condominium complex in Falls Church. Arevalo was visiting from Honduras.
- Benning, Victoria. "Fairfax Sheriff Ordered to Reinstate 2 Deputies." The Washington Post: B.07. National Newspapers Core. Jul 09 1999. Web. 12 Mar. 2012.
- Mustac, Frank. "Stinnette to Leave Office in May after Three Decades with Department." FairfaxTimes.com. Post-Newsweek Media, Inc./FairfaxTimes.com, 5 Mar. 2003. Web. 11 Nov. 2014.
- Smith, Leef. "A Cheery Presence is Missed at School Where Hit-Run Victim Worked." The Washington Post: G09. Dec 11 1998. ProQuest. Web. 4 Feb. 2017.
- Glod, Maria. "Officer Fined $500 in Shooting of Dog; Man Acquitted of Animal Cruelty Charge." The Washington Post: V.03. National Newspapers Core. Dec 13 1998. Web. 12 Mar. 2012.
- "METRO in Brief: Woman, 81, Dies in Annandale Crash." The Washington Post (1974-Current file): 1. Dec 21 1998.ProQuest. Web. 29 Aug. 2016. Note: Reference incorrectly spells Ayres' last name as "Ayers".
- "METRO IN BRIEF: Clifton Woman, 32, Killed in Car Accident." Washington Post. The Washington Post, 21 Dec. 1998. Web. 29 Aug. 2016.
- Smith, Leef. "Teenager Found Dead in Va. Fire." Washington Post. The Washington Post, 23 Dec. 1998. Web. 26 July 2016.
- Jackman, Tom. "Falls Church Woman Sentenced to 14 Years for Killing Daughter." The Washington Post (1974-Current file): 1. Dec 18 1999. ProQuest. Web. 26 July 2016 .
|Fairfax County by Year: 1998|
|November 1998||·||December||·||January 1999|