(CNN) -- The official death toll in last month's massive landslide in rural Washington state rose to 29, up one from the previous day, Snohomish County medical examiner's office representative Kelly Stowe said Wednesday.
About 15 people remain missing, authorities have said.
A rain-saturated hillside along the north fork of the Stillaguamish River gave way on March 22, sending a square-mile rush of wet earth and rock into the outskirts of the town of Oso in the North Cascade Mountains.
The landslide left behind a graveyard in the debris, where bodies have been recovered and crews painstakingly search for people who are listed as missing.
Rescuers have been trudging through the muck, which is 70 feet thick in some places.
Hundreds of people and cadaver dogs are involved in the search, officials have said.
Larry Nickey, one of the incident commanders, told reporters Wednesday that he is increasingly using professional teams with extensive training in searching for human remains, and is scaling back the number of volunteers in the field.
Nickey said searchers are focusing on areas of the grid where they feel there is a high probability of finding bodies.
He said that one body found Wednesday is not yet counted in the official toll.
The search is perilous. The debris field is full of toxic sludge -- a combination of human waste, toxic chemicals from households, propane tanks, oil and gas, according to Lt. Richard Burke of the Bellevue Fire Department.
Every person, animal and thing that comes out of the field has to be decontaminated. Some of the workers have come down with dysentery, and supervisors are concerned that others may be at risk for tetanus.
The weather has been good for the past three days, allowing water to recede from the debris field, but the forecast looks bad, especially for Friday, when the National Weather Service says there is a 100% chance of rain, which will be heavy in spurts.
According to CNN affiliate KOMO, a bank with branches in Arlington and Darrington said it would forgive any home loans and car loans that weren't covered by insurance.
"Coastal Community Bank is ready to stand behind our customers, and if they are not insured and they owe us that debt, we will forgive that debt," CEO Eric Sprink told KOMO.
The station reported that of the dozens of primary residences destroyed, none had landslide insurance.
Gov. Jay Inslee has asked the federal government for assistance, including disaster grants.
As searches continued, a major state university said it was ready to help its students from the area. Washington State University will waive tuition for the next academic year for students directly affected by the slide, specifically students with permanent addresses in Oso or nearby Darrington, university spokeswoman Kathryn Barnard said Wednesday.
The number of students this could affect wasn't immediately clear. Darrington has about 450 students enrolled in its school system.
CNN's Ana Cabrera contributed to this report.