Question:  Robert Eringer worked for the FBI in keeping surveillance on the activist accused of murdering whom?

Context paragraphs:
Robert Eringer: Robert Eringer, born October 5, 1954, is an author, investigative journalist and private-sector counterintelligence operative.  "Salon magazine" described Eringer as an “obscure journalist” with ties to Clair George, the former Deputy Director of Operations of the CIA.  Eringer freelanced for the FBI's Foreign Counter-Intelligence Division to assist with the apprehension of Edward Lee Howard, an ex-CIA officer who defected to the Soviet Union in 1985.  In this ruse, Eringer commissioned Howard to write the "Spy’s Guide to Central Europe".  Eringer describes his assignments for the FBI, which also included keeping tabs on Ira Einhorn, in his book "Ruse: Undercover with FBI Counterintelligence" (2008).

Ruse (book): Ruse is an autobiographical account written by investigative journalist and FBI counterintelligence operative, Robert Eringer.  "Ruse" covers the author's covert interactions with CIA defector, Edward Lee Howard in the late years of his life.  The primary objective is to convince Howard to travel outside of Russia, to a jurisdiction where he could be arrested and extradited.  Eringer's cover as a literary agent also allows him to gain the confidence of the 23 year fugitive, Unicorn Killer (Ira Einhorn).  Frustrated with extradition negotiations, the FBI approved Eringer's plan to keep tabs on Einhorn in case that he would attempt to flee from France during extradition negotiations.  Activities described in "Ruse" also expose Cuban intelligence (DGI) operatives in Washington D.C., and preemptively exposed a Cuban plot to disenfranchise Senator Bob Menendez.  When allegations were made against the Senator in 2012, a short passage from "Ruse", reported in "The Record" in 2008, caused Alex Seitz-Wald ("Salon") to Tweet his theory, and the "Daily Caller" ultimately published information disproving the allegations in 2013.

Monitoring and Surveillance Agents: Monitoring and surveillance agents (also known as predictive agents) are a type of intelligent agent software that observes and reports on computer equipment.  Monitoring and surveillance agents are often used to monitor complex computer networks to predict when a crash or some other defect may occur.  Another type of monitoring and surveillance agent works on computer networks keeping track of the configuration of each computer connected to the network.  It tracks and updates the central configuration database when anything on any computer changes, such as the number or type of disk drives.  An important task in managing networks lies in prioritizing traffic and shaping bandwidth.

Ira Einhorn: Ira Samuel Einhorn (born May 15, 1940), known as "the Unicorn Killer", is an American environmental activist convicted of murdering his ex-girlfriend Holly Maddux.  On September 9, 1977, Maddux disappeared following a trip to collect her things from the apartment she and Einhorn had shared in Philadelphia.  Eighteen months later, police found Maddux's partially mummified body in a trunk in his closet.  It had been packed with Styrofoam pellets, air fresheners, and newspapers.

Mass murder: Mass murder (sometimes interchangeable with "mass destruction") is the act of murdering a number of people, typically simultaneously or over a relatively short period of time and in close geographic proximity.  The FBI defines mass murder as murdering four or more persons during an event with no "cooling-off period" between the murders.  A mass murder typically occurs in a single location where one or more people kill several others.  Many acts of mass murder end with the perpetrator(s) dying by suicide or suicide by cop.

Eric O'Neill: Eric Michael O'Neill (born March 3, 1973) is an American former FBI counter-terrorism and counterintelligence operative.  He worked and was entitled as an Investigative Specialist with the Special Surveillance Group (SSG) and played a major role in the arrest, conviction, and life imprisonment of FBI agent Robert Hanssen for spying on behalf of the Soviet Union and the Russian Federation.  He is a public speaker and security expert who currently lectures internationally about espionage and national security, cybersecurity, fraud, corporate diligence and defense, hacking, pursuing dreams and surviving Hollywood.

Targeted surveillance: Targeted surveillance (or targeted interception) is a form of surveillance that is targeted on specific persons of interest and distinguished from mass surveillance (or bulk interception).  Untargeted surveillance is routinely accused of treating innocent people as suspects in ways that are unfair, of violating human rights, international treaties and conventions as well as national laws and of failing to pursue security effectively.

Timothy P. Murphy: Timothy P. Murphy is an American law enforcement officer and a former Deputy Director of the Federal Bureau of Investigation.  Murphy joined the FBI in September 1988.  He has formerly served in FBI field posts in cities such as Newark, Tampa, Washington, DC, and Cincinnati along with several post at FBI Headquarters.  Murphy has investigative experience in a number of matters including counterterrorism, organized crime and drug trafficking.  His experience also expands into undercover and surveillance work.  Murphy's executive experience includes being the special agent in charge of the Washington Field Office, special agent in charge of the Cincinnati Division, and a member of the Director’s Special Agent in Charge Advisory Committee.

Isaac B. Desha: Isaac Bledsoe Desha (January 1, 1802 – August 13, 1828) was a 19th-century American tanner who was convicted of murdering one man in Kentucky, and confessed to murdering another in Texas.  He was notable as the son of the Kentucky Governor, Joseph Desha.  Shortly after his father's election as governor in 1824, Desha was accused of robbing and killing a man named Francis Baker, who was passing through Kentucky.  Circumstantial evidence implicated Desha, who denied the crime.

Lindley DeVecchio: Lindley DeVecchio (born Roy Lindley "Lin" DeVecchio on April 18, 1940, in Fresno, California) is a former U.S. Federal Bureau of Investigation (FBI) agent in charge of managing mob informants.  DeVecchio worked for the FBI during the Mafia wars in New York during the 1980s and 1990s, eventually rising to head of the FBI squad responsible for surveillance of the Colombo crime family.  He was also responsible for handling Gregory Scarpa, a Colombo capo who had secretly been an FBI informant since the 1960s.

Supporting paragraphs: Robert Eringer Ira Einhorn
Answer: Holly Maddux