Willard R. Sanders appeals his conviction pursuant to a jury verdict finding him guilty of narcotics distribution in violation of 21 U.S.C. §§ 841(a)(1) and 846 (1976). We affirm.
On October 2,1978, a United States Drug Enforcement Agency (DEA) agent, Over-baugh, filed a complaint against Sanders. After a preliminary hearing on October 5, before a magistrate, the complaint was dismissed for lack of probable cause. A federal grand jury, on October 25, 1978, then indicted Sanders in a two-count indictment charging violations of 21 U.S.C. §§ 841(a)(1) and 846 (1976). Count I alleged that on or about October 2, 1978, Sanders distributed twenty-two capsules of heroin. Count II alleged that from May 1, 1978, until October 2, 1978, Sanders had conspired with Rosebud Biggies knowingly and intentionally to distribute a controlled substance. The case was tried to a jury. On December 20, 1978, the jury rendered a verdict of guilty on both counts. Sanders’s motion for a new trial was overruled on July 13,1979, and on July 26, 1979, the District Court1 sentenced Sanders to a prison term of five years and a special parole term of six years. The same sentence was imposed on both counts, to run concurrently.
On appeal, Sanders urges reversal of his conviction on the basis of four arguments.: (1) the trial court erred in admitting as evidence the contraband seized on October 2, 1978; (2) the trial court erred in admitting as evidence the October 2 statement made by Sanders; ■ (3) the trial court erred in admitting as evidence the October 25 statements made by Sanders; and (4) Sanders was denied effective assistance of counsel. The facts relevant to these arguments are set forth in our analysis of the case. Probable cause to arrest
On October 2, 1978, DEA Agents Overbaugh and Thornton waited in a car in the vicinity of Seventeenth and Crocker, Des Moines, Iowa, in order to observe Willard Sanders and Rosebud Biggies. The agents had chosen to conduct surveillance pursuant to information received from a confidential informant that Rosebud Biggies was trafficking in heroin and cocaine, and that he obtained his drugs from Sanders at Seventeenth and Crocker, specifically at the house at 853 Seventeenth Street. The informant indicated that the drug transaction meetings often occurred around noon and provided a detailed description of Sanders’s automobile, including the license plate number. The agents had received information from this informant concerning the Biggles-Sanders drug transactions on at least a dozen occasions, with the most recent tip given only three days prior to the time they conducted this surveillance. The informant had previously supplied other information and had proven reliable regarding other drug transactions. His information had led to at least six search warrants and fifteen arrests and had never been discovered to be false. The agents, who already had some acquaintance with Sanders and Biggies, were also aware of the fact that in 1971 Sanders had been convicted of distributing heroin in an incident connected with Rosebud Biggies.
From a distance of approximately one- and-one-half to two blocks, at about 12:45 p. *1312m., the agents observed Biggies walk behind the 853 Seventeenth Street residence to an area where a door is located. Approximately five minutes later, 12:50 p. m., Biggies and Sanders walked from the house, crossed the street together, and entered Sanders’s vehicle. Sanders occupied the driver’s seat, and Biggies took the passenger seat.
After observing the subjects in the automobile for approximately one minute, without seeing anything happen in the Sanders vehicle, the agents drove their vehicle from their surveillance position to a position in front of Sanders’s automobile. Agent Overbaugh then approached the passenger side of the Sanders vehicle and noticed Biggies make a furtive movement with his right hand from the area of his shirt pocket to the floor of the car in the area around his feet. Agent Overbaugh also noticed that Biggies had an excited facial expression. Immediately after this, the agents announced their identity as federal agents, and Thornton, who was approaching the driver’s side, flashed his gold shield badge to Sanders.
At this point, we find that the federal agents had probable cause to arrest both Sanders and Biggies, or at minimum had a strong and reasonable suspicion that they were engaged in criminal activity.2
[Pjrobable cause to arrest exists when an officer personally knows or has been reliably informed of sufficient facts to warrant his belief that a crime has been committed and that the person who is to be arrested committed it. United States v. Stevie; 578 F.2d 204, 208 n.4 (8th Cir. 1977), aff’d on rehearing en banc, 582 F.2d 1175 (1978), cert. denied, 443 U.S. 911, 99 S.Ct. 3102, 61 L.Ed.2d 876 (1979). * * * When independent sources corroborate the information supplied by the informant, there is probable cause for the arrest. United States v. Bazinet, 462 F.2d 982, 988 (8th Cir.), cert. denied, 409 U.S. 1010, 93 S.Ct. 453, 34 L.Ed.2d 303 (1972). Here, the facts known to the arresting officers plus the information by the informant constituted probable cause.
United States v. Luschen, 614 F.2d 1164, 1171-72 (8th Cir.), cert. denied, 446 U.S. 939, 100 S.Ct. 2161, 64 L.Ed.2d 793 (1980).
Agents Thornton and Overbaugh had probable cause to arrest Sanders and Biggies. A reliable informant had provided information, giving the agents a reasonable suspicion that the meeting between Sanders and Biggies involved distribution of narcotics. Their personal observation of the meeting partially corroborated the information provided by the confidential informant.3 Effective law enforcement required them to follow up on this suspicion. As the agents approached Sanders and Biggies, the furtive movement of Biggies and his contemporaneous facial expression further corroborated the information provided by the informant,4 and the totality of information *1313then known to the agents served to establish probable cause to make an arrest. See Draper v. United States, 358 U.S. 307, 79 S.Ct. 329, 3 L.Ed.2d 327 (1959).
Seizure of the packet of heroin
After Sanders and Biggies were removed from the car, Agent Overbaugh searched the person of Rosebud Biggies while Agent Thornton searched Sanders. Agent Thornton’s search of Sanders revealed no narcotics or weapons, but Thornton did discover some “personal stuff,” a billfold and a small amount of cash. Agent Overbaugh testified that he basically conducted a frisk for weapons. He recovered a notebook and $1,053 in cash from Biggies, then instructed Biggies to keep his hands on the roof of the automobile. At this point the door to the passenger side of the vehicle remained open, and Biggies, with his hands on the roof, stood just to the left of the door.
Agent Overbaugh then looked into the car and observed, on .the passenger side floorboard, a small brown packet. The earlier hand movement of Biggies had prompted Agent Overbaugh to look into the car and directed his viewing. Overbaugh reached in the car, picked up the packet and, examining it, found it to contain twenty-two capsules of brown powder. At this point, Overbaugh placed Biggies under arrest for violating narcotics laws. Over-baugh advised Biggies of his constitutional rights, and asked Sanders if he would accompany the party to the courthouse. The agents seized the car, and escorted Sanders and Biggies to the United States Courthouse.
We find that the seizure of the heroin without a warrant was constitutionally permissible. Based upon reasonableness, the United States Supreme Court has approved a number of carefully crafted excepr tions to the fourth amendment’s requirement that government seizures should be made pursuant to a search warrant.5 Three exceptions have possible relevance to the facts of this case: (1) a search incident to an arrest; (2) the plain view doctrine; and (3) the special rules applicable to automobiles.6 The law enforcement procedures employed by Overbaugh and Thornton were completely reasonable and justified by the circumstances.
After the agents determined that they had probable cause to arrest Biggies and Sanders, the agents ordered them to leave their vehicle and searched their persons. The search was conducted within the immediate vicinity of the vehicle, and the floorboard of the car was within the area of Biggies’s immediate control from which he might have gained a weapon or destructible evidence. After the quick sequence of events whereby the agents secured control of Biggies and Sanders and the contraband, Overbaugh formally informed Biggies that he was being placed under arrest and read him his Miranda rights.
The seizure of the heroin can be justified as resulting from a search incident to an arrest. The search and seizure of the packet of heroin was substantially contemporaneous with the arrest, and the floorboard of the car was potentially available to Biggies. See Chimel v. California, 395 U.S. 752, 763, *131489 S.Ct. 2034, 2040, 23 L.Ed.2d 685 (1969). Cf. Adams v. Williams, 407 U.S. 143, 146, 92 S.Ct. 1921, 1923, 32 L.Ed.2d 612 (1972) (limited weapons search appropriate after Terry stop).
Even if the packet on the floorboard .were considered slightly outside the area under the immediate control of the arrestee, Biggies, plain view of the packet was obtained in the course of an appropriately limited search of the arrestee. See Coolidge v. New Hampshire, 403 U.S. 443, 465-66 n.24, 91 S.Ct. 2022, 2037-2038, 29 L.Ed.2d 564 (1971). The District Court thus properly relied upon the plain view doctrine to uphold the seizure of the packet.
As this court observed in United States v. Johnson, 541 F.2d 1311, 1316 (8th Cir. 1976), the requirements for relying upon the plain view exception are: (1) the article discovered was in plain view; (2) the discovery resulted from a legally justified intrusion; (3) the discovery was inadvertent; and (4) the incriminating nature of the article was immediately apparent. All parties concede that the packet was within the plain view of Agent Overbaugh. Since he had probable cause to arrest Biggies and Sanders, or at the very least had the right to make a limited stop under Terry, it cannot be said that Overbaugh was not legitimately in a position to view the evidence. We therefore need deal only with appellant’s challenges based upon the latter two requirements.
Appellant contends that discovery of the heroin cannot be considered inadvertent because the informant’s information had led the agents to suspect that a heroin transaction was taking place. He contends that permitting the seizure of the packet unjustifiably allows circumvention of the warrant requirement. Appellant makes this argument, even though he strenuously asserts that the informant was insufficiently reliable to provide probable cause.
Appellant’s argument regarding the requirement of inadvertency cannot be countenanced. On the one hand, he argues that drug transactions of this nature function routinely and like precise clockwork, and if agents once • observe a drug deal pursuant to an informant’s information they should be required to bide their time, seek a warrant, and return at the next appointed time and place where they believe a drug deal will be made. On the other hand, appellant recognizes that the informant’s information, by itself, may not have provided probable cause, and that until the time when the agents observed sufficiently corroborating material to create probable cause for an arrest, the activities of the agents can be characterized only as investigation of an informant’s tip. In our view, once the investigation provided probable cause to believe that the agents were observing the commission of a crime, they were not required to ignore the activity and seek a search warrant. The inadvertency requirement’s purpose is to deter planned warrantless seizures not based upon exigent circumstances. The requirement is not met when law enforcement officials “know in advance they will find [the evidence] in plain view and intend to seize [it.]” Coolidge v. New Hampshire, 403 U.S. 443, 471, 91 S.Ct. 2022, 2041, 29 L.Ed.2d 564 (1971). It is inapplicable to the situation at bar, where by surveillance pursuant to a tip the agents determined that they had probable cause to arrest for the commission of a crime currently in progress before them.
Appellant argues that the incriminating nature of the packet could not be ascertained without examining its contents and viewing the capsules of heroin. We reject this argument because we find that the incriminating nature of the brown packet was immediately apparent to the DEA agent. The informant had specifically indicated that Sanders and Biggies dealt with cocaine and heroin. This information, plus Agent Overbáugh’s personal observation of Biggies, the training and experience of the agents, and the particular physical characteristics of the packet7 created a reasonable *1315inference that the packet contained the contraband.
The situation is analogous to that in United States v. Blake, 484 F.2d 50 (8th Cir. 1973). In Blake we found that the cumulative facts of the case would have led a reasonable person to believe that a particular purse probably contained contraband. This, plus the fact that a white plastic bag, known to be a common item in narcotics distribution, protruded one-and-a-half inches outside of the closed purse, sufficed to establish the incriminating nature of the evidence, justifying both the seizure of the purse and the opening of it to find the heroin within the white plastic bag. 484 F.2d at 57. The plain view doctrine did not require Agent Overbaugh to have absolute proof of the incriminating nature of the packet; otherwise even the sight of the capsules would have been insufficient because only a laboratory analysis could prove that they contained heroin. Given the totality of the circumstances, it was immediately apparent to Overbaugh that the packet appeared to contain contraband.
The District Court did not err in denying appellant’s motion for suppression of the heroin as evidence.
Voluntary statements
After arrival at the courthouse, Sanders was asked if he wished to give a statement. He agreed, and Agent Overbaugh read him a statement of his constitutional rights and Sanders read the statement-of-rights form. Sanders indicated he understood his rights and waived them. He then supplied a voluntary statement prior to the agents’ making any decision regarding whether to file a complaint. Overbaugh then filed a .complaint against Sanders and advised Sanders that he would have to appear before the magistrate. On October 3, 1978, Agent Thornton spoke with Sanders about the possibility of Sanders assisting with the investigation in terms of providing more than just general information. Sanders had replied that he was going to investigate the narcotics seized on October 2 and provide assistance.
Following the return of a federal grand jury indictment on October 25, 1978, Over-baugh and Thornton arrested Sanders. At the time of his arrest, they did not again advise him of his constitutional rights, but they did not question him. As they transported him to the Polk County jail, Sanders volunteered the statement, “You know that dope—that drug was in capsules, and you can’t get those capsules in the Des Moines, Iowa, area.”
During trial, Sanders objected to the admission into evidence of his written statement of October 2, 1978, on the grounds of relevancy, and objected to the testimony of Agent Thornton relating Sanders’s state*1316ment made while he was being transported to jail.
Sanders objects on appeal to the admission of the two statements into evidence, on the basis that they were fruits of an illegal arrest and that the statement made during transportation to the jail was not voluntary because it was the product of custodial interrogation and he had not intelligently or voluntarily waived his rights under the fifth and sixth amendments and Miranda v. Arizona, 384 U.S. 436, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966).
While we note that Sanders may not have preserved for appeal the issues he now raises, we find the merits of his arguments unpersuasive.8 As we have already determined that the agents had probable cause to arrest Sanders on October 2, his statement made on that date cannot be considered the fruit of an illegal arrest, and prior adequate Miranda warnings were given. Admission of the October 25 statement was appropriate because the facts established the voluntary nature of the statement. Agent Overbaugh fully informed Sanders of his rights on October 2, after which Sanders indicated that he wished to waive them. At the time of his arrest, the agents did not question him or in any way attempt to elicit information from him. Although Agent Thornton had spoken with him on October 3 regarding the possibility of assistance, this conversation does not present sufficient evidence of any semblance of pressure or coercion or lack of voluntariness of the October 25 statement. See United States v. Grant, 622 F.2d 308 at 316-317 (8th Cir. 1980).
The recent United States Supreme Court decision in Rhode Island v. Innis, 446 U.S. 291, 100 S.Ct. 1682, 64 L.Ed.2d 297 (1980), compels rejection of appellant’s argument that the statement made during transportation to the jail should have been suppressed because the agents did not read him his Miranda rights after taking him into custody. The Court stated:
This is not to say, however, that all statements obtained by the police after a person has been taken into custody are to be considered the product of interrogation. * * * It is clear therefore that the special procedural safeguards outlined in Miranda are required not where a suspect is simply taken into custody but rather where a suspect in custody is subjected to interrogation. “Interrogation,” as conceptualized in the Miranda opinion, must reflect a measure of compulsion above and beyond that inherent in custody itself.
446 U.S. at 299, 100 S.Ct. at 1689. (footnote omitted). The circumstances of this case do not suggest that Sanders was subjected to any compulsion. His prior conversation with Agent Thornton twenty-two days earlier cannot be considered within the realm of coercive police practices designed to elicit an incriminating response from a suspect in custody. Sanders’s statement of October 25 clearly falls into the category of an unsolicited voluntary remark made while in custody but not while under interrogation.
Effective assistance of counsel
Appellant contends that he was denied effective assistance of counsel because his retained attorneys failed adequately to investigate the case prior to the trial. The District Court conducted a hearing on these charges and determined that they were without merit. A careful review of the records reveals no reason to disturb this finding. Appellant has not shown that he was “materially prejudiced in the defense of his case by actions or inactions of defense counsel” or that “his attorney failed to exercise the customary skills and diligence that a reasonably competent attorney would perform under similar circumstanc*1317es.” Morrow v. Parratt, 574 F.2d 411, 412-13 (8th Cir. 1978).
Conclusion
Judgment affirmed.
. The Honorable William C. Stuart, Chief Judge, United States District Court, Southern .District of Iowa.
. The District Court found that these circumstances presented adequate grounds for an investigative stop of the nature endorsed in Terry v. Ohio, 392 U.S. 1, 88 S.Ct. 1868, 20 L.Ed.2d 889 (1968). Terry permits law enforcement officials, without a warrant, to conduct a limited investigation if, on the basis of specific and articulable facts, they acquire a reasonable suspicion that a crime is being committed. See also Pennsylvania v. Mimms, 434 U.S. 106, 110-12 & n.5, 98 S.Ct. 330, 333-334, 54 L.Ed.2d 331 (1977) (reasonable to order occupants from car and conduct limited weapons search). We agree with the District Court that the stop was justified on this basis, but we additionally hold that the agents were correct in believing that they had probable cause to arrest as their basis for the stop.
. As stated in United States v. Gonzalez, 555 F.2d 308, 313 (2d Cir. 1977): “The corroborating evidence need not, of course, establish the crime itself; corroboration of even innocent elements is enough.” See also United States v. Dien, 609 F.2d 1038, 1043 (2d Cir. 1979), reheard 615 F.2d 10 (2d Cir. 1980) (adhered to previous decision).
.As stated in Sibron v. New York, 392 U.S. 40, 66-67, 88 S.Ct. 1889, 1904-05, 20 L.Ed.2d 917 (1968);
[Deliberately furtive actions * * * at the approach of strangers or law officers are strong indicia of mens rea, and when coupled with specific knowledge on the part of the officer relating the suspect to the evidence of crime, they are proper factors to be considered in the decision to make an arrest. Brinegar v. United States, 338 U.S. 160, [69 S.Ct. 1302, 93 L.Ed. 1879] (1949); Husty v. United States, 282 U.S. 694, [51 S.Ct. 240, 75 *1313L.Ed. 629] (1931); see Henry v. United States, 361 U.S. 98, 103, [80 S.Ct. 168, 171, 4 L.Ed.2d 134] (1959).
. The United States Constitution, Article IV, states:
The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
. See, e. g., Chambers v. Maroney, 399 U.S. 42, 90 S.Ct. 1975, 26 L.Ed.2d 419 (1970); Carroll v. United States, 267 U.S. 132, 45 S.Ct. 280, 69 L.Ed. 543 (1925). Because of the confusion regarding the automobile exception, see Arkansas v. Sanders, 442 U.S. 753, 768, 99 S.Ct. 2586, 2595, 61 L.Ed.2d 235 (Burger, C. J., concurring in the judgment); id. at 768-72, 99 S.Ct. at 2595-2597 (Blackmun, J., dissenting), and because the importance of the automobile involved in this case appears minimal, we need not address the issue of whether the situs of the contraband within the vehicle created an exigent circumstance permitting the seizure of the contraband to preclude the possibility of its removal or destruction.
. After the Supreme Court’s decision in United States v. Chadwick, 433 U.S. 1, 97 S.Ct. 2476, 53 L.Ed.2d 538 (1977), courts have found it necessary to pay close attention to the details *1315of the physical description of containers that have been opened by law enforcement agents without a warrant. -In United States v. Ross, No. 79-1624 (D.C.Cir., Apr. 17, 1980), a panel of the United States Court of Appeals for the District of Columbia Circuit considered the difficult question of whether opening a paper bag by the police constituted an illegal warrantless search. Addressing the issue of how to determine whether an expectation of privacy attends a particular container, the court catalogues various types of containers. Id. at 9-13 and nn. 3 and 4. An examination of this catalogue and a reading of Judge Bazelon’s separate opinion concurring in part and dissenting in part highlight the difficulty of making the determination required by Chadwick and Arkansas v. Sanders, 442 U.S. 753, 99 S.Ct. 2586, 61 L.Ed.2d 235 (1979). In this case, however, the physical attributes of the brown packet and the circumstances under which it was perceived render it unnecessary for us to delve deeply into the question of whether it was “inevitably associated with the expectation of privacy,” Arkansas v. Sanders, supra, 442 U.S. at 762, 99 S.Ct. at 2592.
The packet, approximately 2‘A by 3 inches, was constructed from heavy, manila-colored paper and appeared well-used. A part of it had been tom off and the record does not indicate that Agent Overbaugh had to unseal or tear the packet to look inside. The record implies the contrary. Appellant does not in fact argue that an expectation of privacy attended the packet; he limits his argument to contending that the incriminating nature of the packet was not immediately apparent. The District Court’s conclusion to the contrary, however, cannot be considered clearly erroneous. The contents of the packet could easily be inferred from its outward appearance and the surrounding circumstances. The agents knew that heroin or cocaine is frequently carried in small packets of this nature. Biggies’s furtive movement indicated the size and placement of the contraband and further corroborated the information already known to the agents suggesting that Biggies and Sanders were engaged in a narcotics sale.
. The Government argues that appellant did not raise these issues at the trial level and therefore we should not consider them for the first time on appeal. United States v. Librach, 536 F.2d 1228, 1231 (8th Cir.), cert. denied, 429 U.S. 939, 97 S.Ct. 354, 50 L.Ed.2d 308 (1976). We do not wish to imply condonation of this practice, but review is always appropriate under the plain error rule of Fed.R.Crim.P. 52(b), and addressing these issues may aid a principled disposition of similar claims.