The charges pile up against a pair of former Virginia police chiefs, a Cleveland DEA agent has some explaining to do, and so does a Houston crime lab tech who didn't follow procedures and wouldn't take a drug test. Let's get to it:

In Houston, more than 200 drug cases are in jeopardy after a lab technician is accused of "failing to properly secure drug evidence." It's only the latest scandal for the city's troubled crime lab, which has been under scrutiny for the past five years over faulty DNA testing that sent people to prison, the drug and alcohol testing division being shut down after its director failed a proficiency test, and evidence from thousands of cases being improperly stored in the evidence rooms. In the latest blow, the Houston Police Department announced Tuesday that lab tech James Carpenter had been relieved of duty with pay. Carpenter, who worked in the drug lab since 2002, had been recently warned about missing work, and investigators sought him out last week after receiving reports that he "was not handling evidence in compliance with lab protocols." When Carpenter refused to give a formal statement or submit to a drug test, he was suspended. Now, all his work for the past six months -- some 200 drug cases -- is under review.

In Richmond, Virginia, two former Southwest Virginia police chiefs already facing charges were arrested again last week on new drug charges. Former Damascus Police Chief Anthony Steven Richardson was charged with conspiracy to distribute drugs, obstruction of justice, possession of drugs and possession of firearms. Richardson, 40, already faced seven felony counts from June, including distributing methamphetamine. Former Chilhowie Police chief Dwayne Sheffield was charged with distribution of drugs, child abuse/neglect and conspiracy to distribute drugs. Sheffield, 37, already faced charges from May of committing sex crimes against a 17-year-old girl during a Halloween haunted house that raised money for sexual assault victims. The new charges resulted from an investigation by state, local, and federal law enforcement officials, and officials said the drugs involved were mainly methamphetamine and marijuana. Sheffield's wife, Nancy, was also charged with drug distribution, conspiracy, and child abuse/neglect.

In Cleveland, a DEA agent is under scrutiny after one of his informants admitted sending dozens of people to prison with false testimony. Informant Jerrell Bray told authorities in May he had made up testimony and lied on the witness stand in numerous cases, resulting in the dropping of charges in two cases and the release of one prisoner so far. Many more could come. DEA Agent Lee Lucas, who has a reputation as gung-ho drug fighter, is Bray's handler. The testimony of both Bray and Lucas in numerous drug cases is being challenged. Look for more to come out in coming weeks and months on this one.

A Michigan narc is accused of making off with a whole bunch of blow, an Alabama juvenile probation officer is accused of snitching for the bad guys, a Massachusetts trooper takes a plea in a pain pill ring, and a Missouri cop goes to prison for ripping off drug couriers. Let's get to it:

In Detroit, a Detroit narcotics officer was suspended July 19 for allegedly stealing 13.2 pounds (six kilograms) of uncut cocaine from the department's evidence room. Detroit Police Chief Ella Bully-Cummings did not identify the officer, saying he had not yet been charged with a crime, but she did say he had access to the evidence room and was suspected of replacing the coke with another substance. The stolen dope was valued at $2.4 million, she added.

In Tuscaloosa, Alabama, a juvenile court probation officer is accused of taking bribes in exchange for tip-offs on police activities. Fayette County Juvenile Court Probation Officer Denny Driver, 37, was charged with one count of bribery Tuesday. Officials were tight-lipped about what Driver allegedly told to whom, but he was arrested after an investigation by Fayette County Sheriff Rodney Ingle, Fayette Police Investigator Ronald Stough and Drug Task Force agent Mark Allison. Driver has now been fired and awaits an August 13 preliminary hearing.

In Worcester, Massachusetts, a state trooper pleaded not guilty July 19 to charges related to his role in an Oxycontin ring. Trooper Mark Lemieux, 49, a former member of the Bristol County District Attorney's Drug Task Force, is accused of conspiring with his ex-partner in the state police, his live-in girlfriend, and a hired gun to distribute the popular pain reliever from June 2006 to May 2007. He was a task force member from 2002 until December 2006. Lemieux and crew went down after a supplier they had contacted got busted and agreed to wear a wire. Charging documents say police have Lemieux twice picking up money from the dealer while in uniform and in an unmarked police car.

In St. Louis, a former suburban St. Louis police sergeant got four years in federal prison July 20 for his role in a cocaine conspiracy. Former Hillsdale Sgt. Christopher Cornell, 45, was indicted along with five other St. Louis-area men is what prosecutors called a conspiracy to distribute cocaine throughout the metropolitan area. Members of the group confessed to plotting to rip-off low-level drug runners by arranging for shipments to pass through Hillsdale, where Cornell would pull them over and take their drugs. He copped to one count of use of a communication device to facilitate a felony.

The allure of Oxycontin (and its profits) snags two cops, a deputy can't keep his paws off the meth, and a South Carolina cop gets charged with drug dealing. Just another week in the drug war. Let's get to it:

In Louisville, Kentucky, a Lebanon Junction police sergeant was arrested June 25 on charges he planned to sell Oxycontin. Sgt. Daniel Carr, 33, and his girlfriend were both arrested by DEA agents on charges of conspiracy to possess with the intent to distribute the popular narcotic pain reliever. Federal officials said the arrests came after a months-long investigation that resulted in several purchases of the drug from an informant, culminating with a final buy attempt that ended with the pair going to jail. Carr, a career law enforcement officer, was fired immediately upon arrest. He and his girlfriend face up to 20 years in federal prison.

In Newark, New Jersey, a former Newark narc was sentenced to nearly seven years in federal prison June 26 for his role in an Oyxcontin distribution ring. John Fernandez, 37, pleaded guilty in September to one count of conspiring to possess the drug with the intent to distribute. According to federal officials, Hernandez sold more than 3,000 of the pills between September 2004 and September 2005. His defense attorney said Hernandez got the pills legally for injuries suffered on the job, but was persuaded to sell them by another Newark police officer who has also been charged in the case, but has been cooperating with authorities. Hernandez must report to federal prison by July 23.

In Deming, New Mexico, a former Luna County sheriff's deputy got a year's probation for stealing methamphetamine from a motorist. Former Deputy Tommy Salas pleaded guilty June 25 to a misdemeanor count of attempted possession of meth after being arrested in July 2006 for taking the dope off a driver at a traffic stop, but failing to log it in. Salas, who had been on leave since his arrest, resigned his position July 2 as part of the plea agreement, with his attorney saying "he needs to move on."

In Lake City, South Carolina, a Lake City police officer was charged July 2 with drug trafficking and other offenses. Officer Shanita McKnight, 34, went down after an investigation by the FBI, the State Law Enforcement Division, and the Florence County Sheriff's Office. She is also charged with extortion, and faces from 10 years to life in prison on the drug counts. Little other information has been forthcoming.

The Mexican government announced Monday it has replaced the federal police chiefs in all 31 states and the Federal District to determine whether they are fighting drug trafficking or abetting it. The move comes as President Felipe Calderón is now six-months into an offensive against the powerful and violent so-called cartels that has seen more than 20,000 soldiers and police swarm into cities and states considered hotbeds of the drug trade.

The 32 purged chiefs must submit to and pass polygraph and drug tests before being reconsidered for their positions. Their financial status will also be scrutinized. If they pass muster, they must be retrained before being reassigned.

Drug prohibition-related corruption has been the bane of Mexican law enforcement for decades. Now, once again, a purge of police is viewed as necessary by high officials. Just last month, six federal police officers were arrested for protecting cocaine shipments at the Mexicali airport.

"Every federal cop is obliged to carry out his post with legality, honesty and efficiency," Public Safety Secretary Genaro García Luna said at a news conference Monday announcing the housecleaning. "In the fight against crime, we have strategies. One axis of our strategy is to professionalize and purge our police corps."

Nearly 7,000 of Mexico's 20,000 federal police, who investigate drug crimes and homicides, have been assigned to work alongside the more than 12,000 soldiers deployed in Calderón's war on drugs. That police are working side by side with soldiers has raised concerns that they could be undercutting Calderón's campaign by passing information on to the drug traffickers.