OPINION

Martin was convicted under separate counts charging manufacturing and possessing a controlled substance (methamphetamine) with intent to distribute it, in violation of 21 U.S.C. § 841 (a)(1). Rathbun was convicted of possession of heroin, in violation of 21 U.S.C. § 844 . We affirm.

1. Statement of Facts.

On September 25, 1973, an employee of Central Scientific Co. (“CSC”), a scientific supply company in Santa Clara, California, about 40 miles from San Francisco, notified the San Francisco office of the Drug Enforcement Administration (“DEA”) that a person identifying himself as Kenneth Martin and as a representative of San Francisco-based Nevada Pacific Specialties (“NPS”), using an NPS purchase order, personally placed an order for various articles of glassware and chemicals. 1 Items ordered by Martin included chemical glassware and substantial quantities of activated charcoal, acetone, isopropyl alcohol, and vacuum oil.

The next day, DEA agents watched CSC and saw Martin sign in his own name and pay cash for the purchases, to which had been added a quantity of ether anhydrous. Martin had arrived driving a panel truck. The agents learned that the truck was registered to one O’Brian, who had also made purchases from CSC, using NPS purchase orders.

After loading the items into the panel van, Martin did not head for San Francisco. Instead, he drove south, away from San Francisco. He was continually watched, and was seen making two U-turns and several brief stops, but without leaving the car, just before he reached his home in Cupertino. When Martin arrived at his home, he and his wife carried the contents of the van into the house. Shortly after, a red Toronado car arrived at the house.

From about 5:00 P.M., the agents, who had obtained permission from the owner of adjoining premises to enter his yard, stationed themselves behind a fence immediately adjacent to the Martin property. They smelled ether and acetone, heard the running of water and clinking of glassware, saw Martin pouring liquids from one container to another, and saw five-gallon cans, several boxes on a table, and later a jug containing an orange liquid with a white precipitate.

■ At about 7:45 P.M., Mrs. Martin left the house, drove off in a car, and was followed by two agents. Another agent approached the Martin house and knocked on the door. A man answered at a window and the agent asked the whereabouts of a fictitous person. The agent left and rejoined the agents in the neighbor’s yard. The two agents watching Mrs. Martin also returned. Martin then left the house, walked up and down the street, and met Mrs. Martin in the driveway when she returned. The two then drove to a parking lot and parked, facing the traffic and with the car lights turned off. When Martin left the house, the odors of acetone and ether stopped being noticeable by the agents.

*1213 Later, the Martins returned to the house, the odors were again noticeable, and sounds of running water and clinking glassware were again heard.

Rathbun had arrived at the house during the evening. About 11:00 P.M., the agents saw Martin and Rathbun removing some of the items seen in the house and placing them on the back seat and in the trunk of the Toronado, which was parked in the driveway. These included the jug with the precipitate. The two got into the car and drove away. Within a few minutes, the DEA agents stopped the car and arrested them both. A search of the car’s back seat revealed the jug — later found to contain 146 grams of pure methamphetamine — and the agents found a small amount of heroin and narcotics paraphernalia on Rathbun’s person.

After indictment, appellants moved to suppress all the evidence seized. This appeal challenges the district court’s denial of their motion.

2. Probable Cause for Arrest.

Appellants argue that the evidence should have been suppressed because it was obtained incident to an unlawful arrest. Wong Sun v. United States, 1963, 371 U.S. 471 , 83 S.Ct. 407 , 9 L.Ed.2d 441 . Whether a warrantless arrest is constitutionally valid depends upon whether, at the moment of arrest, the officers had probable cause to make it. United States v. McDowell, 9 Cir., 1973, 475 F.2d 1037, 1039 . Arresting officers have probable cause if, at the moment of arrest, “the facts and circumstances within their knowledge and of which they had reasonably trustworthy information were sufficient to warrant a prudent man in believing that the [arrested person] had committed or was committing an offense.” Beck v. Ohio, 1964, 379 U.S, 89, 91, 85 S.Ct. 223, 225 , 13 L.Ed.2d 142 ; United States v. McDowell, supra. In applying these standards, we must consider all the facts known to the officers and consider all the reasonable inferences that could be drawn by them before the arrest. Rodgers v. United States, 9 Cir., 1959, 267 F.2d 79, 85 . The question is one of fact, and each case necessarily turns on its own peculiar facts.

Martin and Rathbun, in their briefs, analyze each bit of information that the officers had, demonstrate ,to their satisfaction that each is innoceht on its face, and conclude that, whether they be considered singly or together, these bits of information do not amount to probable cause. We cannot agree, although we do agree that the case is a close one.

We think that this is a case, like United States v. Patterson, 9 Cir., 1974, 492 F.2d 995, 997 , in which “[t]he succession of superficially innocent events had proceeded to the point where a prudent man could say to himself that an innocent course of conduct was substantially less likely than a criminal one.”

Consider what the officers knew: First, Martin purported to purchase chemicals and supplies for NPS of San Francisco. He arrived in a car belonging to another man who had also placed such orders for NPS. But rather than heading for NPS in San Francisco, he headed in the opposite direction, toward Cupertino. The officers could wonder why.

Second, when Martin got near to his home, he made two U-turns and several stops. The officers could wonder whether he feared that he was being followed. The time when Martin would be most concerned about a “tail” would be when he was nearly home — not when he was en route on major thoroughfares.

Third, at Martin’s home, the chemicals and supplies, which could be used to make methamphetamine as well as many innocuous things, were taken inside.

Fourth, beginning at about 5:00 P.M., and continuing to about 11:00 P.M., Martin and others were doing work which could produce methamphetamine, but could also produce perfectly legal products. The officers could wonder why they were doing what they did at home and during the late evening.

*1214 Fifth, after a fictitious inquiry, Martin went outside, waited for his wife, and when she arrived they proceeded to a place where they could survey the scene. The officers could take this to show a fear of being watched and a consciousness of wrongdoing. 5

Sixth, at tlí'é rather late hour of 11:00 P.M., Martin and Rathbun loaded a jug which could well have contained methamphetamine, together with other things, into the Toronado and took off. Why?

We think that this behavior, coupled with what had gone before, could give the watching agents, as prudent men familiar with the unlawful making of the drug, cause to believe that Martin and Rathbun had committed or were committing an offense. Beck v. Ohio, supra. The stop, arrest, and search were valid because they were based upon probable cause.

3. Invasion of Privacy.

Martin and Rathbun mount one other attack upon the arrest and search. They argue that when the officers looked through and over the fence, and used their noses to smell ether and acetone, they were invading a constitutionally protected zone of privacy — the Martin house. Not so. The officers had a right to be where they were. They did not invade the Martin premises. They saw what they saw because it was visible from where they were. Martin and his cohorts may have believed that they enjoyed complete privacy, but they did not, not because of anything that the agents did, but because of what they did. The neighbor would not have violated their rights by seeing and smelling what the officers saw and smelled. The officers did no more.

No case cited by the appellants goes so far as Martin and Rathbun would have us go here. In the case on which they most heavily rely, the watching agents had unlawfully invaded the defendants’ private property and peered through his windows. Texas v. Gonzales, 5 Cir., 1968, 388 F.2d 145 . Nor does Katz v. United States, 1967, 389 U.S. 347 , 88 S.Ct. 507 , 19 L.Ed.2d 576 , help the appellants. There, agents overheard Katz’s conversation in a public telephone booth by means of an electronic device attached to the outside of the booth. In effect, the device took them inside. We find nothing in the Katz opinion indicating that if an officer had merely stood outside the booth and heard what Katz was saying, Katz’s rights would have been invaded. Eavesdropping from a place where the officer has a right to be is a long-accepted technique of crime detection, not outlawed by the Fourth Amendment. If Katz had talked loud enough to be overheard, his expectation of privacy would be gone. So here the activities in the Martin house were conducted in such a manner as to be seen and smelled from the adjoining property. Whatever expectation' of privacy Martin and his cohorts had was defeated by their own activities. See Ponce v. Craven, 9 Cir., 1969, 409 F.2d 621, 624-625 ; Gil v. Beto, 5 Cir., 1971, 440 F.2d 666 .

Affirmed.

. Both Martin’s and NPS’ names were on a list supplied by DEA to scientific supply cornpanies such as CSC. This fact, however, we disregard. There is nothing in the record as to why the names were on the list.