What better way to get to the bottom of a controversial airplane crash than, er, to ensure all the evidence gets to the bottom of a ditch? New images, some unverified, of the Iranian effort to investigate Ukrainian International Flight 752 show an unusual piece of equipment in the debris field — a large bulldozer. In at least one image, this one retweeted by US Ambassador to Germany Richard Grenell, the bulldozer is moving debris around, which would hardly be an effort to preserve evidence:

No one knows how to clean up a site before the inspectors come better than the Iranians. #PS752 https://t.co/PBOFzwDnYL

— Richard Grenell (@RichardGrenell) January 9, 2020

Another image, taken by the Associated Press, does appear to be verified as authentic and taking place during the investigation. Business Insider’s Lauren Frias notes that a bulldozer running through the debris field would make it “next to impossible” to determine what happened to Flight 752:

Iran has used bulldozers to move around pieces of debris from a crashed Ukrainian passenger jet, possibly destroying evidence that could help prove what happened to the doomed flight.

Images and reports from the crash site, just outside the Iranian capital, Tehran, show at least one bulldozer working in the debris at the site, where the Boeing 737-800 crashed Wednesday morning, killing all 176 people on board. …

Giancarlo Fiorella, a researcher for the investigative website Bellingcat, shared a thread of photos that he said showed heavy machinery at work.

“I find these photos distressing because this could potentially be the scene of a crime,” Fiorella told Channel 4 News.

“If this was a shoot-down event, you don’t want to disturb the crash site before a thorough investigation can be conducted, and I’m not sure that one has been conducted.”

Bellingcat had done some key open-source investigative work in the wake of another anti-aircraft shootdown of a passenger jet, the Malaysia Air crash in Ukraine in July 2014. The Australian news outlet News.com.au interviewed Fiorella as well, and reports that Bellingcat claims to have verified the images that Fiorella has been pushing out on social media, including the one tweeted by Grenell, as having at least been “geo-located” to the crash site:

(Deleted previous tweet to clarify terminology)

Images of heavy machinery in use at the #PS752 crash site: right (35.561029, 51.104018) and left (35.559296, 51.104630)

Sources: https://t.co/FKfLwnbePQhttps://t.co/n8nUUT75SH pic.twitter.com/rJmGdsYsg8

— Giancarlo Fiorella (@gianfiorella) January 9, 2020

Open source investigation website Bellingcat, whose painstaking work linked downed MH17 to Russia back in 2014, said it had verified images of a bulldozer clearing a debris field in Shahedshahr on the outskirts of Tehran.

There are now concerns evidence has been compromised, contaminated, or worse, destroyed, and the truth about how and why the aircraft crashed may never be known.

“Those images (of the bulldozer) we were able to geolocate to the crash site,” Bellingcat investigator Giancarlo Fiorella told Channel 4 News.

“I found them to be really distressing because this is potentially the scene of a crime. If this was a shoot-down event, you don’t want to disturb the crash site before a thorough investigation can be conducted and I’m not sure one had been conducted.

“The presence of heavy machinery at the site and the bulldozing is very distressing.”

Are they really bulldozing the debris? The Ukrainians apparently think so, although it has been only lightly reported thus far and might require more verification itself. A Ukrainian journalist reports that a source on the country’s investigative team tells him that the Iranians have been using bulldozers to pile up the debris in an assembly area, which will eradicate most of the usefulness of reassembly:

Yuriy Butusov, journalist and editor-in-chief of the Ukrainian publication Censor.NET, wrote on Facebook, citing a source in the Ukraine’s State Investigative Commission, that the plane wreckage at the crash site is being bulldozed, and expressed doubt that Iran is interested in thorough investigation into what happened.

According to Butusov, at 12.00 pm, his source informed that the Ukrainian experts were at the crash site. Another group went to Iran’s air traffic control center to inspect the radar footage.

“Is Iran interested in a thorough investigation? It’s not clear. Wreckage of the aircraft is continued to be bulldozed and delivered to the assembly site. There is a crowd of different people in uniforms and without uniforms at the crash site, hundreds of people collect and carry away fragments of the plane, this process is not under any control,” the source said.

The Ukrainian expert reports from Iran that the fragments of the plane are dumped indiscriminately in the pile, from which experts need to extract the pieces and lay out the remains of the hull.

So are we sure that’s what’s going on? Well, it’s not as if anyone expected a thorough and credible investigation from Tehran anyway. Earlier today they categorically ruled out the most obvious answer to the mystery, which is that their anti-aircraft personnel overreacted and shot the flight down by mistake. The initial photos from the scene tended to support that thesis, showing larger pieces of the fuselage riddled with holes, just as with the Malaysia Air flight shot down by a similar system six years ago. And what purpose would a bulldozer serve at the crash site at all, when the evidence requires careful handling for the reassembly and later analysis? Just the presence of the bulldozer raises serious questions about the intent of its use.

Still, however, we are only getting dribs and drabs of this. Even Fiorella isn’t quite ready to call this a case of cover-up, but he’s very concerned— both about the crash itself, and the propensity of people to jump to conclusions. Wait for the evidence to get verified, Fiorella advises:

That’s good advice under any circumstances, but perhaps particularly so in these.